Game crashimg after updating system

I have a Samsung A16 (Mediatek Helio G99 MT6789) and I've been playing Star Rail on this phone for almost a year. I had One UI (I think) 7.0 and today (foolish me) I decided to update it to 8.5. First, I updated it to 8.0 and Star Rail crashed, so I updated it to 8.5 and nothing changed. The crashing happens when battles have been going on for a while; every time a character uses an ultimate, the performance gets worse until it crashes, and sometimes I manage to win the battle and that's when it crashes (the results aren't saved). This is a big problem for me, as it makes it impossible to beat the endgames, and I don't know if there are also crashes during the story cutscenes. Please, if you can help me by telling me what to do, I would be very grateful. Star Rail is the only game I play, and it would really hurt me not to be able to play it on my phone. And please, I know Mediatek is a meme, but it was working perfectly until yesterday, so that's not why it's crashing.