I’m experiencing the same issue. Where the activities view gets stuck and you can’t get out of it. I can close down apps and even launch new ones, log out etc. but you can’t interact with any application because it is stuck in Activities view. Not exactly sure what the entire “trigger” is because it doesn’t do it 100% of the time which I’m sure is how it made it’s way to stable.
I found this link where others where experiencing the same issue:
There are also several reporting freezing. It’s kind of to be expected as gnome 40 is a major change in the gnome workflow so it’s not surprising it has broken lots of extensions. That’s just the way it goes sometimes. Only thing to do is isolate the extension and then work with the extension’s author/contributors to hopefully get them working soon.
I did find that I could switch to a different TTY (Ctrl-Alt-F3) and then type the following to disable the extensions to at least allow me to get back into my system without having to restart after activities hijacks the system.
gsettings set org.gnome.shell disable-user-extensions true
Then you can either re-enable them either through the extensions app or using the following command:
gsettings set org.gnome.shell disable-user-extensions false