Gnome Software not working in Fedora Silverblue 36 with “Your operating system is no longer supported...” message

Side-note, as I guess may be related and you still have that “harder” setup: You can simplify rpmfusion updates, like to Fedora 36 a lot, so you don’t need to uninstall and reinstall the rpmfusion repos etc. (That may also fix your upgrade issue there.)