The question is in the title. The only thing I did was updating from a 2020 version to 2021 LTS.
It is a game for Android
Could be many reasons, but yes - performance will probably vary each release depending on what features were added or optimised and so on.
Stuff changed, so performance changes.
You should profile both before and after. Obviously you have a backup, like everyone does before upgrading. Profile it to see where the performance you expected went.
Also, phones will vary in performance based on heat and other factors as well.
But I don’t get how it can change this much. I have the game made in the 2020 version installed on my phone as well as the game made in the 2021 version. So 2 apps. It works smoothly in the 2020 one but not in the 2021 one. It’s the same game, just with different versions.
Here’s the thing, no-one else gets it either. We can’t. You have to do the profiling, or report a bug, as you have not supplied any specifics.
I found out that if I set the Application.targetFrameRate to 60 it works as before
For the future, this kind of General problem should be posted on the Editor & General Support. The fact that your game is 2D doesn’t mean the issue is related to a 2D feature unless you have a profiler running that clearly indicates it’s a 2D feature causing it.
As it turns out, it wasn’t related to 2D.
That alternate forum would also give you a wider audience for your post.