that was a demonstration, the same behaviour was observed on the non-admin account, regardless of whether Mods is also in about page hidden groups
yes, site-wide administrators disappear and the moderators has one numeric member not listed, when looking on the admin account, despite Who can see this group? and Who can see this group’s members? both being set to Group owners, moderators, and members
the full name for the Mods group is Our Moderators.
I’m proposing change here, where any user in a group in about page hidden groups cannot be shown as a member of a group on the /about page as being in any of the about page extra groups