The Flathub remote is available to users who opt-in to enabling
third-party software repositories in either GNOME Initial Setup or
GNOME Software.
A lot of flatpaks in Flathub have debatable quality, and are closed source. If we could
wait until flathub separates open-source and proprietary repos, the open-source one could
be unfiltered, and the proprietary one could have a blacklist for very bad packages. I
think it would be better if there could be some sort of warning in GNOME software, so
maintainers could mark certain packages as unsafe or low-quality.