I’m starting to suspect there is a bug in GNOME Shell where the overview occasionally gets “stuck”. No key press or widget click will exit the overview mode. I have to log out and log back in. Launching new windows still works, but the window immediately gets arranged into the overview.
I first noticed this behavior when I tried out the Pop!_OS 21.04 beta, and dismissed it as a bug in the beta. But now I’ve seen it twice in Ubuntu 21.04 proper. Has anyone else noticed this behavior?
Can confirm that I have also encountered this issue in 21.04. Also, I have never experienced anything similar in the previous releases, so it looks to be a new issue in 21.04. @spc, if you report the issue on Launchpad as @rs2009 recommends, please cite the link to the new bug ticket here.
Just a tiny workaround: instead of logging out and logging back in, you can press Alt+F2, type ‘r’ in the invoked command line and press Enter. This restarts GNOME Shell. In my case, it helped.