Just wanna highlight a few things because I see people either saying their display is fine, while others are saying theirs is yellow.
1. A yellow display doesn’t necessarily mean that it’s defective, it’s more likely a calibration issue (or non issue according to Apple).
2. If you’re not comparing against another display, you will most likely not notice the yellowness. There’s no single representation of the colour white as it’s affected greatly by lighting conditions. So saying that your iPhone is fine without comparison is pointless.
3. This year’s iPhone 12 and 12 Pro displays are very uniform, and their colour shifting when you tilt the phone is very minimal. They’re just calibrated to be warmer, that is all.
4. If you decide to compare against a store display unit, make sure to take your other device that you initially compared your new iPhone against. If your other device is also cooler than the display unit, then there’s no point exchanging the phone. Remember, the display can either seem cooler or warmer at certain times because of the light conditions, likely because of the display coating at Apple uses.
Edit: 5. When you take a photo of 2 displays side by side, it’ll most likely not be the same as what your eyes are seeing.