On a side point, I changed the colour profile in Chrome which seemed to fix the issue when snipping from Chrome (which was my main issue). I've also tested snipping from Word (which obviously a change in Chrome shouldn't impact... ) and that was also fine.
I went to here: chrome://flags/#force-color-profile
and changed the colour profile to sRGB (the below screenshot was a snip with HDR on, and as you can see... it's now fine)

Give it a go.. see if it sorts it for you.
Yeah, it was Snippets of Chrome (for QA work) that suddenly stopped working. This was following accidentally hitting the "Clear Clipboard" option in the edit menu of Irfanview. Turning the HDR/SDR slider down (to the left) helped with that screenshot, but made the rest of Windows unusable. So, I turned it back up to where it screwed up the screenshots. After 30 to 45 minutes, when I took the next set of screenshots, they worked fine again.
I will DEFINITELY try YOUR way next time it happens!
What I've pegged the problem as is this: that various applications will randomly respect (or ignore) the SDR/HDR slider, then switch to ignoring (or respecting) the slider, then back AGAIN! I suspect this is NOT a Chrome issue or an issue with any other app. My hunch is that is has to do with the way the Windows kernel REPORTS the state of the slider TO THOSE APPS.
I base this off of the fact that after EVERY SINGLE restart of Windows, HDR display is f---ed up, and even the slider won't fix it. However, if I don't touch anything, and wait until the monitor turns off (I set it to a 1 minute wait), then jiggle the mouse to turn the screen back on, Voila!, all fixed. In the reestablishing of the connection to the monitor, the HDR/SDR slider is PROPERLY queried, thus solving the problem, until something random happens and HDR support on Windows fails . . . AGAIN!