U2520D, Mac mini M4, sleep mode, distorted image issue

I have a problem with Mini Mac m4. I have a U2520D monitor, after screen saver runs, after sleep mode, after changing color profile settings etc. the image is distorted and everything looks like 8bit screen image.

When "Put the display to sleep when screensaver activates" is selected in monitor properties, it works fine. However, when the computer goes into sleep mode for a long time (10-12 hours), the same problem occurs.