I have noticed this change sometime ago, but didn't really pay much attention, however, it is becoming distracting. In the Phone app, under the Favorites tab, the contact tiles have very bright (washed out) background, which makes the text rather hard to read. When you press and hold one of the tiles in order to rearrange it, its colors normalize for a second. Not all tiles are affected equally. Seems like it might be a bug.
Pixel 7 Pro