Either I'm dreaming, but as long as I've been posting here, I believe I've seen a few "full member" labels revert to "regular member." Is this something that has been requested by a member, is a temporary sanction, is permanent, or can be all of these? I've wondered about that lately. Any insight would be appreciated.
I think it's because their old account was deleted or they asked for it to be deleted started over and used the same name they did in the past .
What you witnessed was most probably a sanction, permanent or temporary. Such decisions are taken from time to time to protect the security and integrity of the community.
There are circumstances where members lose full member privileges. And there are cases where members ask for the restriction. And, as stocking said, a member who self deletes and leaves, then comes back with same name will be a regular member until meeting the requirements anew.