Linux Mint and Steam

I am coming from windows and want to switch. Got a new M2, installed mint cinnamon, got it to dual boot, installed the drivers for my 3060 installed steam.

I linked the steam libraries on my other drives (the ones I also use in windows) downloaded proton in several versions and... Cyberpunk didn't start. When I restarted the system, updated all the software, restarted again.

When started steam again, the UI was gone. I see three icon in the tray on the right, and I can move the steam window, when I happen to find it. But I don't see the window, I see the desktop background. What can I do to fix that?

Thanks for your time and help