I've got a Pixel 2 running Android 9 (Pie). The other day the colors for the contacts on the Phone/Dialer Favorites screen switched to what I can only describe as 'pastel'. They don't match the contact colors in the Messages App (though the used to). Switching a contact color in the Messages App has no effect on the new pastel color for the contact in the Phone/Dialer.
I don't think I fatfingered anything to cause this but I'm not going to swear to it. When I noticed it I had just picked up the phone and unlocked it to make a call.
Color Inversion (Accessibility) is not enabled. Dark Mode is not enabled. Phone is totally stock.
What caused this and how do I revert it?
Co-worker with a Pixel 2 that recently upgraded to Pie noticed the same thing. It's quite possible the change happened at the same time for both of us (not at time of upgrade but a few days after). Is this something Google did? Something about Material Theming with the new Material Design they rolled out, pulled and rolled out again? Also, I've restarted and done a power off, so I don't think this is a transient glitch.
Co-worker's Messages app has gone Pastel, mine has not so far, despite force stopping the Contacts App, the Phone/Dialer and Messages and doing a restart and power off. Phone is 23.0.208561757, Contacts is 22.214.171.124518734, Messages is 3.4.048 (Yehu_RC26_xxhdpi.arm64-v8a.phone).
Yet another co-worker (Pixel 2 / Pie) has the same symptoms as me (Pastel Colors for contacts in Phone/Dialer only). So it seems this is definitely something to do with some kind of rollout of something by Google.