Then you definitely have some settings wrong.

Make sure the monitor is set to HDR mode (in the monitor’s built-in settings), and the OS is set to treat the monitor as HDR. Depending on the OS there may be other things to play with. E.g. I was getting the issue with things looking washed out after the latest bazzite update until I manually installed VK_HDR_LAYER

Here is a site I usually use to test that HDR is working correctly: https://www.wide-gamut.com/test (you may need a chrome based browser, Firefox doesn’t always render it correctly)