(Split off bug 6192) Distributions are trying to simplify X authentication and discourage running things as root. As such some X servers are configured to only allow connections from a specific user: > $ xhost > access control enabled, only authorized clients can connect > SI:localuser:ossman This breaks our installer and tl-setup as they run as root and therefore cannot access this X server. Bug 6192 makes sure we fall back to text mode when we detect this problem, but ideally we would like to have a graphical installation for these systems as well. Note that this is mostly seen with Xwayland, but it could happen for any X server. Also note bug 6192, comment 9 which states that Xwayland might start allowing root in the future.
And GNOME has now pushed a commit allowing sudo X11 stuff: https://gitlab.gnome.org/GNOME/mutter/commit/a8984a81c2e887623d69ec9989ae8a5025f7bd47
This seems to be fixed now. I can start tl-setup just fine in a Wayland session on RHEL 9.