It is very important that you use Proton GE and have lib32-nvidia-utils installed. I use endeavouros (arch-based distro), so I just installed "proton-ge-custom-bin", then used it in Steam (Library -> right-click on Predecessor -> Properties -> Compatibility -> Tick "Force use of a specific Steam Play Compatibility Tool" -> select "Proton-GE"). I also installed "lib32-nvidia-utils", without it the game tries to launch and does nothing and stops.

I was able to play just fine. If you experience input lag, try stopping your compositor (e.g. picom, compton, etc.) if possible before launching the game.