Sorry that the image in Photoshop becomes grayed out when you switch to another app on your computer.
Which version of Photoshop 2020 are you working with? In Photoshop, you can check that by going to Help > System Info. Latest is v21.1.3
Please uncheck the option "Use Graphics Processor" under the Preferences> Performance menu in Photoshop and see if the issue persists.
If that does not helps, you may try restoring the preferences for Photoshop & see if it helps? See this article for reference: https://t.co/ulJI7cGn1G You may want to backup your settings beforehand: https://t.co/4dX7gkr36D