These days: the system adds and removes the forum ID specified in game (via the
FORUMID command). If the permissions seem to get confused, you can always force access removal & reinstatement by using
FORUMID RESET.
3+ years ago: Access to various subforums was previously a totally manual process. In theory, this meant a user's forum ID was manually added to membership of the appropriate groups (and subsequently removed when characters left the relevant faction). In practice, however, some forum IDs had their permissions specially modified to allow direct access to these forums - these are ones I've kept an eye out for and cleaned up as needed. I don't think there's any left these days; it was just a case of access management in a time when there was little documentation and automation to guide various admin folks.
For now, I've removed WickedWitch from the Midnight group manually - let me know if your access is reinstated by the system for some reason and we'll investigate further.