We're sorry about the trouble with Photoshop 2019 while tools. Would you mind telling us which macOS version you're working on? Please update Photoshop to the latest available version through the Creative Cloud desktop app to check if the issue persists.
If it persists, you can try disabling the option to Use Graphics Processor from Photoshop by going to Preferences, then Performance. Once done, quit & relaunch Photoshop to check if that helps.
Thanks for the info! Photoshop 2019 is not optimized for macOS Big Sur. Please update Photoshop to the latest version (22.4.2) & also update macOS to the latest version (11.4) & let us know if the issue persists.