As I already said in my previous post. The latest version of the game messed up an FPS for a lot of people. The guys who have RTX 3080 and had 140 FPS two updates ago, now have around 40 FPS. So try to downgrade two versions back. Pay attention that if you play multiplayer than you won't be able to play it on public servers. You can still play it only if you and your friends are running the same version and play on your own server. The single player is not a problem to play.
Here is a guide on how to do it, read the whole post, the second post have a versions table:
