v20 Thumbnails on Color page oversaturated and contrasty

This is new since I upgraded from 19. The same thing happens on another machine using Sonoma. The thumbnails do not represent the grade of my grading monitor like they used to. It's almost like they're in a different color space—super contrasty and lots of chroma. I'm using DaVinci's automatic color management setting. I tried other color science methods, and every time, the thumbnails were way off.

TIA for your help. I hope it's not a bug, and it's something simple.