FPS occasionally tanks until I disconnect and rejoin game on Linux

[ExistingExpert]

Pretty consistently, whenever I am playing any hero, the fps with suddenly drop to around 15. I always have to disconnect and rejoin the game to solve the issue. Interestingly, whenever this occurs, the fps appears to be working fine in the "esc" menu but is reduced while actually playing the game.
Also, I am running this on Linux with proton.