I had to restart steam once before the game would launch. I also started using proton expirimental the first time (I tried that before restarting steam). It now launches with the default proton without problems.

Looks like I will be able to play without any problems. The game once notified me that my "framerate is too low for multiplayer" (In the menu, not during gameplay). I don't know how multiplayer works yet, so I can't check if that is actually a problem.

Other than that, the game runs without problems for me. Performance seems fine. I left the settings unchanged and play on "high".