DIAGNOSIS The monitor is accepting an HDR signal but cannot display it properly. This is an entry-level HDR implementation without local dimming or high peak brightness.
FIX For most content, leave HDR OFF in the monitor's OSD 'Picture' settings. In Windows, turn off HDR in Display Settings. If you must use HDR for a game, enable it in Windows/game first, then on the monitor. Then, in the monitor OSD, manually raise Contrast to near max and adjust Color Temperature to 'Warm' to counteract the washed-out look.
IF THAT DIDN'T WORK The washed-out look is inherent to the panel's limited contrast and brightness. This model's HDR is a basic signal compliance feature, not a performance feature. There is no fix.
HEADS UP Forcing HDR on in Windows with SDR content will make your desktop look terrible. Only enable it system-wide for native HDR games or videos, then disable it after.