Bazzite is just straight up a better experience than SteamOS. Fedora backend with rpm-ostree is way better than what Valve has going on. And for Steam Deck, GNOME just makes more sense for touch interfaces.

Bazzite defaults to Plasma for Desktop Mode just as SteamOS. According to universal-blue.org/images/bazzite/installation/ Gnome is only the 4th installer choice.