I got a suggestion at: (And this allowd Gnome to start for me)
https://bugzilla.redhat.com/show_bug.cgi?id=1960937#c12
[ Jonas Ådahl] 2021-05-26 20:32:39 UTC
Try adding DRIVERS=="radeon", SUBSYSTEM=="drm", TAG+="mutter-device-disable-kms-modifiers" to /usr/lib/udev/rules.d/61-mutter.rules and remoot.
As I am using Silverblue, which /usr is readonly.
How can I modify udev rules under Silverblue?
Updated below:
OK. I find out how