I ran into a problem when a user has a project in his root folder which was earlier in a folder that has been deleted but has not been yet erased. This results in a situation when I can't unshare this folder from a user or group because it is considered as shared via parent folder. It is difficult to pinpoint the exact deleted folder which causes such behavior. I can only find by reading through comments.
I see two solutions to such a problem without changing the behavior of deleted folders (I understand that it is needed to save structural dependencies for possible restoration of the folder)
1 have visible tags of deleted folders for admins (different visual cue, for example, s̶t̶r̶i̶k̶e̶t̶h̶r̶o̶u̶g̶h̶)
2 have a separate category in "sharing interface"
we now have:
"Folder shared with X groups and X people"
"Parent folders shared with X groups and X people"
You could add "Deleted parent folders shared with X groups and X people" (see pic)
Also in Right click menu interface with regards to sharing.