How has your local area changed due to immigration?

Guess the poll was too much of a thought crime. Hope Starmers thought Gestapo don't come after me....

In my current home I haven't really noticed any. I'm Scottish and a bit remote, not really a first choice for anyone arriving in the UK.

I'm sure the scotch government will be happy to prove you wrong in the near future.

I really don't think they will. There simply isn't anywhere near the infrastructure required when you get more rural, no matter how welcoming a government wants to be. (Scotland is big and our pop density is small, I overall don't mind if people move or seek aid here)

In my city, I would say there are several areas that have been ruined by immigration.
I don't think the problem is immigration in and of itself, but rather the way in which it has unfolded. Two main problems stand out to me:
By "British / European values", I mean principles that we take for granted like respect for laws, regulations, and civic etiquettes: Not littering, obeying traffic rules, forming orderly queues, earning an honest living and so on. British culture involves following these rules even when they're not actively policed - ideally out of consideration for others, but if not then at least due to social pressure / fear of silent judgement.
The problem is, not all cultures operate this way. Some cultures adhere more to adages like "every man for himself", "rules are made to be broken", and "it's only a crime if you get caught". In some parts of the world it's not at all unusual for people to defecate on the street, let alone littering. So few people follow traffic laws that they may as well not exist. The informal cash economy makes it the norm for people not to pay tax. Bribery of police officers and public officials is commonplace. And I'll stress that it's not just a few rogue individuals doing this on the sly; corruption of this sort is embedded in the local culture and there's hardly any stigma attached to it.
If immigrants from these places were able to adopt British values in these matters, I don't think there would be a problem. This happens naturally when interacting broadly with the native population and people from cultures besides your own; you learn from each other and a common culture develops with the best aspects of all of them. But this becomes difficult when immigrants cluster in isolated communities. Schools, workplaces and businesses filled with immigrants from the same background prevent exposure to common British norms from outside their communities. It's no wonder that many immigrants have been able to live in the UK for decades without needing to learn English. It's not true diversity or multiculturalism, it's ghettoisation.
The result of this is visible in certain areas where civic norms seem to have broken down entirely. Instead of one person cheekily parking on the double yellow lines, there will be a whole row of 10-20 cars on them. There's nothing unusual about cars being parked in a cycle lane, at a bus stop or in the middle of the road itself. Paid car parks get turned into free ones by people vandalising the ticket machines. Pavements get blocked by unauthorised stalls selling counterfeit goods. Most businesses claim that "the card machine not working" and ask for "cash only" because it's harder to tax. Shops continue to sell expired items on their shelves (and if you point it out to them, they'll offer a discount and try to sell it to you anyway). Litter piles up and attracts rats despite bins being available. The GP surgery I worked at was inundated with fraudulent requests for sick notes or disability claims to exploit benefits. I could go on.
Rules only work when most people agree to follow them, and the few who don't can be dealt with. But when an entire subsection of society routine flouts the rules because their culture allows for it / encourages it, enforcement becomes almost impossible. Local authorities end up having to just turn a blind eye, leaving those areas to decline further.

What city is this?

In my city, I would say there are several areas that have been ruined by immigration.
I don't think the problem is immigration in and of itself, but rather the way in which it has unfolded. Two main problems stand out:
(1) immigrants coming from cultures which are at odds with British / European values, and
(2) those immigrants being concentrated in specific areas, rather than evenly distributed across society.
By "British / European values", I mean principles that we take for granted like respect for laws, regulations, and civic etiquettes: Not littering, obeying traffic rules, forming orderly queues, wearing your mask during a pandemic, earning an honest living and so on. British culture involves following these rules even when they're not actively policed - ideally out of consideration for others, but if not then at least due to social pressure or fear of silent judgement.
The problem is, not all cultures operate this way. Some cultures adhere more to adages like "every man for himself", "rules are made to be broken", and "it's only a crime if you get caught". In some parts of the world it's not at all unusual for people to defecate on the street, let alone littering. So few people follow traffic laws that they may as well not exist. The informal cash economy makes it the norm for people not to pay tax. Bribery of police officers and public officials is commonplace. And I'll stress that it's not just a few rogue individuals doing this on the sly; corruption of this sort is embedded in the local culture and there's hardly any stigma attached to it. It's so easy to think "well, if everyone else is doing it why shouldn't I?".
If immigrants from these places were able to adopt British values in these matters, I don't think there would be a problem. This happens naturally when interacting broadly with the native population and people from cultures besides your own; you learn from each other and a common culture develops with the best aspects of all of them. But this becomes difficult when immigrants cluster in isolated communities. Schools, workplaces and businesses filled with immigrants from the same background prevent exposure to common British norms from outside their communities. It's no wonder that many immigrants have been able to live in the UK for decades without needing to learn English. It's not true diversity or multiculturalism, it's ghettoisation.
The result of this is visible in certain areas where civic norms seem to have broken down entirely. Instead of one person cheekily parking on the double yellow lines, there will be a whole row of 10-20 cars on them. There's nothing unusual about cars being parked in a cycle lane, at a bus stop or in the middle of the road itself. Paid car parks get turned into free ones by people vandalising the ticket machines. Pavements get blocked by unauthorised stalls selling counterfeit goods. Most businesses claim that "the card machine not working" and ask for "cash only" because it's harder to tax. Shops continue to sell expired items on their shelves (and if you point it out to them, they'll offer a discount and try to sell it to you anyway). Litter piles up and attracts rats despite bins being available. The GP surgery I worked at was inundated with fraudulent requests for sick notes or disability claims to exploit benefits. I could go on.
Rules only work when most people agree to follow them, and the few who don't can be dealt with. But when an entire subsection of society routine flouts the rules because their culture allows for it / encourages it, enforcement becomes almost impossible. Local authorities end up having to just turn a blind eye, leaving those areas to decline further.

Birmingham (specifically, areas like Small Heath, Alum Rock, Sparkhill)

Dodgy parking? Vandalising stuff? Selling knock off goods out of car boots? People asking for cash in hand? Dumping litter in alleyways? Disability/benefit fraud?
This was the norm in the working class almost exclusively white area I grew up in. You are using examples that make it sound like immigrants are doing a good job of integrating themselves into the British way of life.

To sort of echo what Gazpacho said, I'm curious why you think these things are "British / European values"?Take littering as an example. Can it really be said that immigrants have "ruined" cities for doing something that plenty of British people would (sadly) be doing anyway? Disrespect for one's environment is not unique to immigrants.

I don't think any of these things are unique to immigrants or that British / European people don't also do them. Obviously not all immigrants do these things either, even within the communities I'm talking about.
My point is more about the scale at which this sort of thing happens. There will be rule-breakers in any community, but if they're a small enough minority then it's easier to take action against it. When rule-breaking becomes normalised in a community, it becomes much harder to control. (And then people start to learn that the rules aren't enforced, and it becomes even more normalised and on it goes). For example I think there's a difference between a couple of people parking on double-yellows and rushing back before a traffic warden sees them or putting their hazard-lights on as a semi-apology, versus an entire cycle lane full of parked cars as if that's what cycle lanes are for. In one case, it's clear that rules are being broken; in the other, it looks more like the rules don't even exist.
The reason I associate it with immigration is because naturally, different cultures have different ideas and emphasis on what is okay and what is not okay to do in society (e.g. most people understand that littering is wrong, but Singapore is far more anti-litter than even Britain is, whereas certain parts of India are completely on the other end of the spectrum). And when people from other cultures migrate to the UK, naturally they will bring their own mindset with them. Normally, they would also pick up ideas from the native population and start to "do as the Romans do" to some extent, but the specific ghettoised pattern of immigration that has taken place in these areas of Birmingham doesn't really allow that to happen so much. You can spend days exploring a place like Alum Rock, and then count the number of White British people you came across on one hand.
When you look back at some of the places that these communities have originally come from, it's clear to see that those places suffer intensely from the issues I'm talking about - unimaginably more so than anywhere in Britain or Western Europe until you experience it for yourself. In Britain, I can hardly think of a time when I've ever seen a motorcyclist without a helmet. In Mumbai, you'd be hard-pressed to find a motorcyclist with a helmet. In fact within easily within the first few hours you'll see a family of five people balanced one on top of each other riding a motorbike designed for one person. Obviously it stems from systemic issues like poverty, but either way people get desensitised to it, leading to a very lax cultural attitude towards road safety than we have here. There are many issues like this, which people end up accepting as a normal part of life and not attaching anywhere near the same social stigma to the individual behaviours that cause them. So it's no surprise to see that in Birmingham, the areas that suffer from these issues the most seem to be the ones which are most densely populated with immigrants from these parts of the world, who live largely in isolation amongst themselves and who are insulated against the influence of wider society.

What makes you think these problems wouldn't exist if these places were populated by British people?

I don't think the problems wouldn't exist, I just think they'd be much less pronounced and far easier for local authorities to deal with.
It's very noticeable in Birmingham that the areas which suffer from these problems the most are the ones which are populated almost entirely by one major immigrant community from either somewhere in the Asian subcontinent (or East Africa, but to lesser extent). Whereas the areas which are populated mostly by native British people or a representative mix of British people and immigrants from a wide range of places don't have these issues to the same degree. Furthermore my grandparents migrated from India to Small Heath decades ago when it was still predominantly populated by the Irish, and according to them these problems were far less pronounced then too.
Then having visited some of the places that those communities have originated from on the Asian subcontinent, I can see that similar problems exist there, but amplified drastically compared to what we see here. And having experienced the culture personally (as I said, I'm descended from immigrants from the same sorts of places myself), I can see the cultural desensitisation against these sorts of issues having been brought to the UK as well.
As Gazpacho says, there may well be places in the UK populated by mostly White British people that also suffer from these problems to some extent. I think poverty and lack of education are big systemic factors that play a part in it, and they can affect anybody. But the areas of Birmingham I'm talking about contain those factors and additionally contain a culture that is far more tolerant of the behaviours that cause these problems (which has come from even more impoverished and even less educated parts of the world).

Given the factors involved, poverty and education perhaps being the most important, what makes you think that the background of these people has makes any significant difference?
It's not just that you're saying these problems have been pronounced by the background of the immigrants (something which you haven't any real evidence for, so far all variables are confounded), you've gone as far to say that these people have "ruined" your city. That's an extremely strong remark to make.

I think I already explained that.
Firstly I'm of the same background myself (or rather, my parents are), so I have personal experience of the cultural attitudes associated with these issues.
Secondly, I've been to those parts of the world and spent enough time there to be able to see what happens to the towns and cities when they're populated by people with those cultural attitudes (and vice-versa, how living in those towns and cities shape their cultural attitudes).
And thirdly because in Birmingham, areas which have not been ghettoised by these cultures appear not to suffer from these problems anywhere near as much. (They might do a little bit, especially if they're less affluent areas. But as I said, there's a difference between areas where some people break the rules, and areas where the rules appear not to even exist).
Poverty and lack of education is a common factor in areas that suffer from these problems, but culture is as well.

The variables in this case are largely confounded, plus your experiences will be limited purely to your own environment (in other words your sample size will be small).

I don’t think the variables are confounded as such. I see poverty and education as underlying variables rather than confounding variables. That is, they influence an area via their influence on the culture rather than independently.
An area being poor / less educated doesn’t automatically mean people have to litter or park badly or do any of the other things I mentioned. But there are various reasons why it might give rise to a culture of people who are less respectful of the civic environment. But that’s exactly why I think background is relevant; some people are recently migrated from backgrounds which are even poorer and less educated than you could ever imagine finding in a first world country like the UK, and the culture reflects that.
I agree that the sample size is small - this is just an opinion from my personal perspective rather than a scientific proof.

By confounded I mean that the variables overlapping and that it is difficult, if not impossible, to determine which one has an influence on a situation (if any). There could be plenty of things affecting what you've seen, including poverty, education, employment / job prospects, crime, the quality of local services, the existing state of the community (prior to immigration) and, as you say, cultural attitudes.

It remains a pretty strong statement to say your city as been "ruined" by immigration, especially if this is based on a hunch.