Comment 0 for bug 1868911

$ dpkg-query -W gnome-shell
gnome-shell 3.36.0-2ubuntu1
$ lsb_release -rc
Release: 20.04
Codename: focal
$ _

When I toggle in and out of the overview on an empty workspace, windows from other workspaces appear. They are not interactable, so this seems more like a rendering bug than the windows really being teleported to another workspace. Switching back to another workspace that has windows causes the ghost windows to disappear. Opening a window in the empty workspace makes it appear on top of the ghost windows, and I have to switch to another workspace and back again to make only the new window be visible.

I am using the vanilla "GNOME" session type. I did not observe this behaviour with gnome-shell 3.35.91-1ubuntu2.

As well as the annoyance factor, of course there's a privacy angle to showing random windows at surprising times.