Extreme sibling rivalry

I just wanted to check to see whether this level of sibling rivalry, or I guess just not getting along, is normal between two very different people or not...

I have a younger sister, who has become increasingly agressive and obnoxious to everyone in general but especially towards me.

I have always been more quiet and hard working, achieving good grades at school, despite getting bullied and she has always been more blunt and assertive and not so academic so I don't know if this is a jealousy thing but I am certainly not a confident person so I find it hard to believe.

I have recently returned back from a long period away travelling and I am getting more and more *****y looks and snide underhand comments than ever before. She has told my parents in the past 'I don't know why you're praising her for that' in front of me for various things, will sit quietly on her phone and make a point of being moody at my celebrations like graduation etc. and raises her voice at simple diasgreements over things like where to eat, who gets to sit in which seat in the car etc. We are both in our 20s and I am finding it hard to cope with her behaviour.

I feel more and more angry and resentful and all the while trying to keep calm and be nice.

She has no problem telling me to 'shut up' or 'piss off' if I try to defend myself, even in public and has muttered similar things to me under her breath when we are alone, even if I haven't said anything.

Anyone have any advice?

She sounds like she has a problem at the moment, I am not sure that I would classify it as sibling rivalry but she is clearly being bothered by something. How old is she? Could it just be her going through her difficult teenage phase?

We are both in our 20s.

I know she has had depression in the past and I try to bear it in mind but her behaviour is different towards me than towards other people, which suggests she can control it.