user services are started for the "gdm" user under systemd

I think we want to use systemctl enable --global for enabling user services automatically in package post-install scripts, however something about the gdm user or ?? causes systemd to start these user services for that user too. For example, after logging in, there are two instances of pipewire started (when using !5142 (merged)): one for the user that just logged in, and one under gdm user. The gdm user should be a system user, so this needs to be debugged

The gdm user is created by Alpine's gdm package, and it seems to be a system user.. uid=32. So why does systemd start user services for this?