Worked great out of the box. No tinkering needed.
Some small text is visible at the first menu/launcher
No-one playing this online, but joined a server with no issues.
Game just opens with a black screen
PROTON_NO_D3D11=1 %command%
When opening the game, I just get a black screen. I have no clue if it's just a graphical bug, or if the game just doesn't work via proton anymore
gamemoderun %command%
Played several games online with friends and experienced no issues.
Working out of the box
Added launch command PROTON_USE_WINED3D11=1 %command%
Doing what Xarvatium suggested will make the game run. However, it runs a little bit slower than on Windows 10 (same specs)
Does not work out of the box.
Dips in FPS with AA enabled
Using "PROTON_USE_WINED3D11=1 %command%" like Xarvatium suggested works on my PC. It does not work at all on my laptop (Ubuntu 20.04, i5 3230, Nvidia NVS 5400 with driver 390.144).
The game throws a Unity error but by using this flag "PROTON_USE_WINED3D11=1 %command%" it boots to menu and you can begin playing.
The game runs well out of the box, with the only problem seeming to be the controller's triggers getting stuck occasionally.
Controller inputs seem to get stuck sometimes. More specifically, the triggers sometimes lock up for a few seconds, which results in the car becoming almost uncontrollable. I also had a problem once where my controllers triggers had flipped, so L2 was R2 and vice versa, but i haven't been able to reproduce it after it happened.
Started the game worked without any problems audio cars menus settings everything works out of the box. Performance is the same as on normal windows.