PLEASE UPVOTE THIS SUGGESTION IF YOU'D LIKE TO SEE IT IMPLEMENTED
It would be convenient if an extra field could be added to user accounts for an admin or mod to leave a comment about the user. The field can be set so that only admins can see it, or mods and admins. It will be visible in the ACP and also when looking at the profile page, but only by mods and admins.
It would be helpful if the field could be formatted with the post editor rather than just HTML tags and will have a large character count capacity, not just 256 characters or similar. The field wouldn't affect the function of the account in any way.
Here's some examples to clarify:
Comment field: this user has been banned twice for trolling and serious disruption. If it happens a third time, make it a permaban.
Comment: this user is always very helpful and contributes a lot to the forum. Consider a promotion soon, make them feel valued.
Comment: this user appears to be subtly trolling and disruptive, but is careful to avoid crossing the line, avoiding warnings. Keep a close eye on them. Will talk to the user in private. Warnings and banning may be appropriate eventually if the behaviour doesn't stop.
Comment: this user donates generously to our Patreon page, so treat gently and carefully. If any issues arise, do not take action, but refer issue to FTL to look into