What has occurred is due to the change of UID_MIN AccountsService has decided that your existing user (501) is now a system user. GDM has then decided that there are no user accounts on the system, so has triggered gnome-initial-setup to create one.
I suspect if you had rebooted after changing UID_MIN back it would have worked fine (user showed in GDM, gnome-initial-setup not run).
I'll assign this to the 'login' package which has decided to change the MIN_UID to 1000 - it may be this is an issue on older systems that used to have this value.
What has occurred is due to the change of UID_MIN AccountsService has decided that your existing user (501) is now a system user. GDM has then decided that there are no user accounts on the system, so has triggered gnome-initial-setup to create one.
I suspect if you had rebooted after changing UID_MIN back it would have worked fine (user showed in GDM, gnome-initial-setup not run).
I'll assign this to the 'login' package which has decided to change the MIN_UID to 1000 - it may be this is an issue on older systems that used to have this value.