For anyone under Linux who can't launch the game I advise to use Proton-GE and paste PROTON_USE_WINED3D=1 %command% in the launch settings.
I happen to get up to 30 fps lock at random and I'm currently figuring out a way to fix that.
Edit:
Trying different versions of Proton didn't help me, the fps lock fixed itself after trying random things but I have no way to determine what did it.