Actually, current Privacy Groups is a plugin. It allows to make named lists of contacts. What is ineteresting this is integrated in Hubzilla core and allows setting access to these lists.
So the first question if if this is core functionality or if there can be another plugin called Circles which makes Hubzilla allow setting access to Circles side by side with Privacy Groups.

These lists are different from forums (which are set organically by activity of contacts), so renaming Forums to groups while having Privacy groups would be strange and need complex explanation what is the difference for somebody who is not used to the concept of channels (Mastodon users).

The Privacy groups are just for personal contacts organising and cannot be addressed with @... But a message can be sent to these lists via lock icon. A bit inconsistent and i think the lock should not be used for posts audience while they are sent out and it does not control access to them but addressing. Lock should be used just for the files.

I see several inconsistencies in this. If these list should be a core functionality, if they are for setting access or can be addressed also. In fact, the Privacy groups or Circles for some strange kind of private Celebrity Soapbox. So the question is if this should be cleared and integrated fully as another channel behavior.