Hi everyone, I have been following this thread for about a week. I've bought an iPhone 12 pro, I've compared it to my brother's iPhone X (both phone with TT off, NS off etc.) and my 12P definitely has a disgusting yellow tint.
Same thing when I've compared it to a Huawei 10 mate pro (OLED display), a Samsung Galaxy A50 (OLED display), a Samsung S6 (OLED display), a macbook pro 13, an iPad pro, a LG monitor (IPS display). The most similar display that I've found is the one of the Samsung S9 (OLED), which has a warm white too, but is still better than my iPhone 12P.
I understand that with OLED display one can have a warmer colour balance, but this yellow tint has nothing to do with a warm white. These iPhone 12 display are just bad quality panels.
Also, I've got the issue where pixels are not completely turned off with black pictures at brightness under 100%.
If I had to guess, I would say that Apple just increased the tolerance range when testing the calibration of the displays in order to accelerate the production and release iPhone 12 in October/November (if I am not wrong, at some point rumors suggested November/December as iPhone 12 release date). Maybe performing a very good calibration that gives perfect white takes much more time and for this reason Samsung and LG are just decreasing the quality of the calibration since Apple allows them to do it by increasing the tolerance range. I don't know, I am definitely not an expert, so I'm just guessing and I know that my reasoning may be completely wrong.
One more (sad) thing. I've tried to watch a few videos simultaneously on the 12P, the Huawei mate 10 pro and the LG IPS monitor. In dark and semi-dark scenes (actually in every scene apart from outdoor scenes with sun shining) the colours on the Huawei and the LG monitor basically look the same, while on the 12P it looks like if I am watching the scene through a green bottle glass. This cannot be just a different choice of calibration. This is just horrible and unacceptable for a 1000$ device. Man! Even a Samsung galaxy s6 (release date 2015) does a better job! Way better!
I don't think this is the same greenish black issue that lots of people have, since in dark setting menu the black and the grey are just fine.
I'm going to return the 12P back and sadly I don't think I will buy another one...