This notification is a regression. Here are my investigations /usr/lib/systemd/system/
gdm.service => BusName=org.gnome.DisplayManager lightdm.service => BusName=org.freedesktop.DisplayManager Gnome-shell don't check yhe bus to talk to. I suspect this is the cause https://metadata.ftp-master.debian.org/changelogs//main/g/gnome-shell/gnome-shell_3.38.4-1_changelog gnome-shell (3.33.90-1) + Call GDM’s RegisterSession() after startup (LP: #1798790)
