I have created a space for my department to use as a team space. I have restricted the access to this space and I have restricted the access to pages that I have added to the space. However the space now seems to be used by other users that should not have access to the space and creating pages making the space very cluttered.
Hi @melanie brehmer , welcome to the community!
Could you please provide more details on how you manage the space permissions? To be more precise: If you have granted access only to the users (or group) that belong to your team and have not granted any access to Anonymous Users, your space should be locked the way you want. (The term Anonymous Access on the bottom of the space permissions page is misleading. It means access to all users not defined by group or user permissions.)
One way to get "unknown user" is to delete someone from your user directory - Confluence will display "unknown user" when there's no name it can look up (this is one reason we recommend disabling leavers, rather than deleting their accounts)
That only applies for looking at the history though - a deleted user can't get in to continue making changes.
The other way to get unknown user is being discussed by Nicolai already, I've nothing to add to that conversation!