I ran this for about 1½ hour at maximum graphical quality yesterday playing online multiplayer with two friends (who are both on Windows I believe) via Proton 5.0-9, and the game ran absolutely smoothly. I second this whitelist request.
proton 5.0-9x1 2020-08proton 3.7-4x1 2018-08
Distro: Manjaro XFCE 17.1.12
GPU: GTX 1060, Nvidia proprietary driver 396.54
Resolution: 1920x1080
RAM: 8GB
Proton 3.7-4 Beta
All is fine and Xbox Controller work !
No MP tested