Hi,
We're sorry about the trouble with Photoshop. Since you're using macOS Catalina, please go to the System Preferences for your Mac, then Security and Privacy, then select the Privacy tab. Then select Accessibility from the list to the left & check if Photoshop is added to the list with a check mark in front of it. If Photoshop is not a part of the list, please add it by unlocking the window first using the lock at the bottom left, then clicking the + icon & navigating to the Applications folder. Also, grant permissions to Photoshop under Full disk access located in the same list as Accessibility. Once done, restart the Mac & check if it helps.
You can also try to optimize the preferences of Photoshop using the steps suggested here: https://helpx.adobe.com/photoshop/kb/optimize-photoshop-cc-performance.html
If the issue persists, you can try to reset the preferences of Photoshop using the steps mentioned here: https://adobe.ly/2Qzc0K3
Please backup your settings prior to resetting the preferences. You can check: https://adobe.ly/2vNz6FG
Let us know how it goes!
Regards,
Nikunj