I don’t think Fedora has a “stable” channel. It has “testing” repo from which updates are pushed to “updates” repo after approval, and that’s it. My understanding is that ublue’s “latest” channel follows Fedora’s “updates”, while “stable” seems to update weekly (though it’s unclear what happens if a package update arrives in Fedora just before “stable” image is about to be built)
Haven’t used GNOME for a while, but I guess that’s a problem of open source projects in general. Though GNOME at least has Red Hat behind it.