There seems to be an inconsistency in how the package xorg-x11-xinit and Gnome mutter handles user permissions for the X server. A few months ago, mutter changed their default behavior such that users are not automatically added as "SI:localuser:<username>" with the motivation that some applications can bypass the X11 permission settings. See https://gitlab.gnome.org/GNOME/mutter/-/commit/b61b0478f7538db27c35dff48f4581a811458116. In Fedora when starting Gnome with X11, "xhost +SI:localuser:<username>" is set at login by the script /etc/X11/xinit/xinitrc.d/localuser.sh, which is a part of the xorg-x11-xinit package. The script was added to the package 16 years ago, but I can't find any information about why it was added. See https://src.fedoraproject.org/rpms/xorg-x11-xinit/c/6cf01551afb21a2de9a54fb009d910bb7595fa08. This now means that there is a difference in security settings in Fedora depending on if users decide to use Gnome under X11 or under Wayland. Can adding "SI:localuser:<username>" still be considered safe? Or do you have any additional info on why localuser.sh was added initially? Reproducible: Always