The Applications screen freezes when I open and close the folder

This problem was reported on Launchpad as Bug #1872268 "Gnome Shell completely freezes in Ubuntu 20.04 when clicking outside of app icon folders (when ubuntu-dock is loaded)".

In comment #25, Rson explained a temporary solution

I have this same problem. I made a video with the problem and the solution here:

https://www.youtube.com/watch?v=J3N9lnGMj-8

The bug is caused by the Ubuntu Dock extension. Changing the extension for the dock to not occupy the entire height of the screen solved the problem.

What I did to resolve it was:

1. Install dconf

   sudo apt install dconf-editor
   

2. Go to /org/gnome/shell/extensions/dash-to-dock/extend-height

3. Deselect the "Use default value". And set "Custom value" to "False".