I noticed last week that one of my portable monitors has HDR so I enabled it and enabled HDR in Windows. It does seem to improve the quality of contrast, especially for videos. This system is set to turn monitors off after 30 minutes. When they wake back up the HDR seems to be disabled (image looks very dim and dull) but in windows display setting HDR shows as enabled. If I turn it off and then back on HDR returns to normal. I don't know how much of this matters but this system has 2 monitors (main is the HDR one), is on a Nvidia 2060 and is on Windows build 20H2 488. I am about to check 508 but I don't expect that to matter. To reproduce this you would need to have HDR enabled and your system set to turn monitors off (but not sleep) after inactivity. When the monitors turn back on HDR will show enabled but be disabled, if you can confirm this bug.