

Right, there’s the immutable root aspect. Guessing the other answer you got fills in the missing piece there and that Silverblue perhaps mounts the system flatpaks on a different r/w filesystem than the read-only /. Check output of mount to see.
At the end of the day it’s up to you if you prefer to keep the system clean and run flatpak unprivileged, or centralize updates under root.
The one catch I can think of with flatpak --user is that it obviously won’t work if /home is mounted with noexec, which is otherwise a good security measure (and IMO not doing that defeats a lot of the security wins of immutable distros). Unless you apply the same mounting strategy to the flatpak xdg user dirs, which is certainly an option but not something everyone will bother with. But then again maybe that’s exactly what you want anyway to make your Flatpak installations smoothly portable across distros.




With your edit that yields a succinct proof that things are nuanced 😉