It's acclimation. I've been through four 11 Pros and finally staying with fourth one, though I'm still not completely pleased with it. When updating to 13.2 beta there was no change in the display at all. However, I am getting used to the display being different than what I expect each time I look at it. Even though I'm still paying attention to the color of the whites, I'm finding that it's easier to move past it and just get back to using my phone. I do still notice the difference. As someone else said, the whites are more like an ivory with True Tone off. But my brain is "sticking" less on the off-white. It's less jarring to me because I'm starting to get used to the screen and expect it. But the screen itself has not changed.
I feel exactly the same, I'm completely use to the display color now.
The only problem is when I use my MacBook / Monitor and switch between that and my phone, it's really apparent how yellow it is for a minute until your eyes acclimate again.
I do think Apple can adjust this via software but I don't think they will.