Nothing relevant in pacnew files, AFAIK.
This part of journal
00:12:28 gdm-session-wor: GLib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
00:12:28 gdm-session-wor: GLib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
00:12:24 gdm-session-wor: gkr-pam: unable to locate daemon control file
00:12:18 gnome-session-b: Unrecoverable failure in required component org.gnome.SettingsDaemon.XSettings.desktop
00:12:11 gdm-session-wor: GLib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
00:12:01 gnome-session-b: Unrecoverable failure in required component org.gnome.SettingsDaemon.XSettings.desktop`
made me find this, so i tried
dbus-launch gsettings reset org.gnome.clocks world-clocks
like reported by @Chrysostomus, and then rebooted.
The issue is still there, but at a first impression i have to wait longer for GDM to crash: about 10 seconds, which is enough to accomplish login