Diagnosis
Windows HDR is active, but the monitor is not in its HDR image mode. The monitor must be in the correct mode to properly tone-map the HDR signal. The default SDR modes will display HDR content incorrectly.
How to Fix It
First, enable HDR in Windows: Settings > System > Display > Use HDR > On. Then, use the monitor's rear joystick. Open the OSD. Navigate to Professional -> Image Mode. Select the mode labeled HDR. The OSD will briefly display "HDR On" in the top-left corner.
If That Didn't Work
Adjust the Windows HDR brightness slider. With HDR enabled in Windows and the monitor, go to Windows Display HDR settings. Under "HDR content brightness," move the slider while viewing typical HDR content (like a game) to find the best balance. Also, ensure you are using a DisplayPort 1.4 or HDMI 2.0 cable.
Heads Up
In HDR mode, most OSD color settings are locked. This is normal. The peak brightness for HDR on this monitor is approximately 550 nits. Desktop SDR content will appear washed out with Windows HDR enabled; you can toggle HDR off via Windows shortcut Win+Alt+B when not consuming HDR media.