Disable other controllers in Steam Big Picture, ensure that your gamepad works well in Big Picture. Ensure - Elden Ring (righ click) -> properties -> Controllers -> Use Steam input on.

Fix: max clock on gpu and cpu. How: CPU: install corectrl go to cpu ->performance scaling - custom -> Frequency governor - Performance GPU: if you are AMD GPU user: in corectrl Performance mode - fixed - High For Nvidia you can find maximum performance setting in "Nvidia settings" as I remember

Exit out of game via Game's "quit game" results AMD GPU RX 6900xt crash. Just kill it game :) (In KDE Easy to do with CTRL+ALT+ESC and click on game)

To actually play (Easy-Anti-Cheat workaroung) a game you need in game's folder: Remove 'start_protected_game.exe' Copy 'eldenring.exe' with name 'start_protected_game.exe'

Ensure that steam didn't redownload 'start_protected_game.exe' if you still get EAC Init error.

So, no online until proton folks make a fix