Apple introduced a new security feature in MacOS Catalina (10.15) requiring explicit consent before allowing apps to record information from the computer screen. Because of this, you might get a message asking you to grant Photoshop permission to record the screen. This permission is only required if you want to use the Eyedropper tool in Photoshop to sample colors from other apps. If you do not grant permission, then you will be limited to sampling colors from within the Photoshop app.
To change the setting on a Mac, go to System Preferences > Security & Privacy > Privacy > Screen Recording and check the box by Adobe Photoshop. If you are unable to check the box, click on the lock icon at the bottom of the panel first to allow changes.
