

mouse para de funcionar no jogo quando vc aperta shift+tab ou alt+tab

Used Proton 6.3-5, worked seamlessly
run in windowed mode instead

Just couldn't get it to work.
Tried several Proton versions, vanilla and GE. With some, it wouldn't launch, with others in full screen mode It shows the main menu for a second then drops back to the desktop. The Steam client still shows the game to be running. In Window mode it stays in the menu but when I start a game, it only shows a plain whit window, doesn't seem to load.
The game works perfectly. Only notable issue, the taskbar being drawn on top of the game, but that may not be an issue on other DEs or WMs.
On Linux Mint 20, the taskbar was drawn over the game and there was not way to make it disappear. At one point, the game screen got shifter up cutting an upper portion of the screen. Tiny annoyance, but still there.

Unable to join any server from main menu
PROTON_USE_WINED3D=1; Custom Proton: Proton-5.11-GE-3-MF
runs great!
I tried playing with bots and a match online - just works.
Nothing happens after lunch main menu.
Install, run, play. It's the same soldat as before, just easier.
Default proton threw "steam must be running" error, forcing 4.11-13 worked flawlessly