The follow plugin can have following notifications and visibility into who is following who hidden with the settings included… but it’s not currently possible to restrict that plugin to admin use only… so, not ideal
Another option may be to fight fire with fire and use AI Triage to monitor specific users.
Triage could be configured to only apply to users in a specific group, so you could have a “suspicious user” group that only admins can see… and feed every post/edit from a member of that group into AI for analysis based on a custom prompt. Based on the output of that the relevant post can be flagged for moderation. This could help with the moderation itself, rather than only providing notifications for manual review. You could have the AI check for new links and flag based on that for example.
If you don’t want to involve AI you could use the Automation plugin configured in a similar way to send a chat message referencing new posts from a certain group in an admin-only channel.
None of these fit the request exactly but get sorta close.
We could possibly add a new automation script that simply flags posts from people in certain groups, we have one that flags posts based on words within posts… so it might just take some minor adjustment to remove that requirement.