Washed out colors in macOS, but HDR looks great

Thanks. The replies from the two Community Specialists is as good as it's going to get on this site, but I don't think they completely understand the nature of the problem either.

I can think of no reason Finder windows would appear "washed out" and dull while videos and (possibly) other images don't. The question of how or why the monitor would render them differently remains unanswered.

It's a classic example of finger-pointing. Apple says "not our monitor, not our problem" while Asus says "that's how Apple renders images, not our problem either".

Lacking any definitive answer I tend to agree with you: there is something about Finder windows that lack the ability to render HDR content the way you are expecting that monitor should render them.

Follow the links leroydouglas provided. Gather the patience to describe the problem in a way they understand and gets past their first layer of support without arbitrarily dismissing your concerns. Perhaps they will forward your concern to a macOS engineer that may take an interest in it.