As protection against certain problematic users who are creating a lot of alt accounts with inappropriate and abusive usernames, I have turned on the setting marked “Staff must approve all new user accounts before they are allowed to access the site.”
However, even though I haven’t yet approved a particular account, that account is still listed as an option when e.g. sending messages or during “@username” autocompletes, and hence is visible to other users.
Is this intended behaviour? I would expect that unapproved accounts are kept isolated from the rest of the users.
In any case, how can I prevent these usernames from prematurely appearing anywhere in the forum before they have been approved?