Okay so as it turns out this isnt actually chess.com's fault.
I checked it in Edge and it looks completely fine, looks like Chrome's newest upgrade (more like downgrade, GJ Google!) screwed up more than I thought.
Green board bright yellow highlight


I'm having this same problem. In puzzle battle the highlight is suddenly so blinding that I can't even look at it. But it's not a problem across my browser, because in standard puzzle rush the highlight is still like it was before. It's just a change in puzzle battle that happened a few days ago, and has rendered the function virtually unusable.
Hello,
Wanted to play some puzzle battles today, but the bright yellow highlight on the green (default) board is so annoying its unbelievable. And no, I dont want to remove highlighting or change boards, im very used to those.
Can you please revert your color changes on the highlights, or at least give an option to change the highlight color?