Comment 2 for bug 1964976

Me (upstream g-r-d) already predicted this, as soon as I saw that Ubuntu ships mixed versions (gnome-control-center-41 (g-c-c) for GNOME 42 (that's unsupported upstream and as seen here breaks things)).

For GNOME 42, we finally switched over to the RDP backend in g-r-d. As a result the UI in g-c-c has been redesigned (https://gitlab.gnome.org/GNOME/gnome-control-center/-/merge_requests/1205#note_1393775).
To not also unintentionally listen on VNC in the background without the notice of the user, the gsettings were adjusted, so that each g-r-d backend has its internal switch (default: off).

You can check that by checking both g-r-d's and g-c-c's version. Upstream we make sure that things won't break in the major version. This means that all components need to have the same major version (i.e. g-r-d-42 + g-c-c-42 + ...-42). Minor versions are just bugfix releases.

Jeremy and Marco of the Ubuntu Desktop Team are already aware of this from our discussion on IRC. It's up to Ubuntu now to act. The remote desktop is not the only thing that breaks here downstream due to mixed versions.
According to Marco, Ubuntus decision would either be to backport the g-r-d UI changes or adjust their g-c-c build to use VNC again.

Some more info on the RDP backend in 42: https://gitlab.gnome.org/GNOME/gnome-remote-desktop/-/issues/26#note_1396166