Same issue. I am in the middle of trying to reinstall Bazzite (I messed up my current installation) and then the built-in keyboard went unresponsive. Unplugging all of the expansion cards (and the charger) then rebooting got the keyboard back.
My best guess for fixing this (as a user) is to unplug the charger and then reboot. I’m using one of the earlier AMD models, I believe 7040 is the name.