You haven't 'lost' 40 marks - you start with zero and build them up, not the other way around. A minor point but an important one. It's not like school, next to nobody ever gets a 100. I've had two in my life and that was on a professional course where the available grades were set at six points: 50, 60, 70, 80, 90, 100.
You're right re the feedback though and I understand the frustration. The feedback will be substandard whereas the mark will likely be about right. This is often down to time constraints and being unable to get into nitty gritty in terms of written responses: markers often just do not have the time and so tend to focus on positives. This is nice but often very unhelpful. Worth noting that in my experience, for every one student complaining that the feedback is too positive, there are four saying it's too negative - it can be hard to strike a balance.
With that said, I don't want to make excuses for what is ultimately a bit of poor practice. You can take the marked piece to an office hour and ask for practical direction on how to improve. Next to nobody does this but it is by far the most direct way to get the feedback you need. 60s are good first year results, whichever way you shake it.