Yup, actually now another puzzle piece falls into place.
On March 11 I posted what seemed to me to be a bizarre email from the Copyright Agent that they couldn’t even verify me as the owner the very items I uploaded.
How is that possible?
Did my user name not appear under those items?
After today, now it makes sense that the key word here is “owner”.
Now it makes sense that email was a prelude to what happened today.
Items in groups that I do own got removed. Groups without an owner got ignored.
So how are they verifying ownership? The user that uploaded them or the inventory where that item is based, a group or a user.
Maybe ownership is defined by who owns the group now?
So it shows Roblox has been working on this for quite a while.