But..this whole issue is with true tone off. Let me guess, didnt take the time to read?
If its super cool with TT off, you dont have this issue. Also, sell one of us your phone.
I actually have read 90% of this 44 page thread, including the OP. But I've also had three of these myself (12, 12, and 12p), from three separate sources (online and local retail), and taken them and compared them (using the OPs test) to display models at a couple of large local retailers as well (all in the DFW area). Not a single one looks yellow when True Tone is off. Are some a tad warmer than others? Sure, but the differences have been minimal and difficult to see. Maybe "warm" equates to "yellow" for some people. And when compared to a cooler white LCD screen, that's understandable.
The screen is either better or it isn't. Yellow and dingy isn't better, end of story.
Every OLED out there is going to look at least a little warmer on whites than a good LCD panel, and more "contrasty" as well. So if you prefer LCD to OLED, which is fine, then none of these panels are going to be ok to you. I have a hunch a decent number of the people dealing with this issue are coming from an LCD panel from the 11, Xr, or earlier like the 7 which was very cool due to not having True Tone.
IMHO these displays are too warm, but I don't necessarily see this as a massive widespread problem. It likely is a problem with a small segment of devices, as is often the case with new devices and OLED panels. But the problem is being skewed larger due to so many people coming from LCDs saying, "Yeah, now that you mention it, my screen does look yellow. Wth?" - when their screen is likely as intended, they're just not used to the warmer OLED look.