Hi there,
Sorry that Photoshop 2021 locks while trying to use " ` " as your push and Distort key.
It seems that the particular keyboard shortcut is not working correctly.
Which exact version of Photoshop are you using and what is your computer's OS?
Would you mind checking the steps mentioned in this article https://helpx.adobe.com/photoshop/kb/keyboard-shortcuts-stop-photoshop-mac.html and let us know if that helps?
Thanks,
Akash