The different tolerance levels of different sourced manufacturers could be the reason software
I’m thinking, if this issue is not every single device of same version running same version OS, it could be different sourced parts from different manufacturers where there is a variation in accepted tolerance levels. This is then exaggerated by buggy programming that’s not picked up in-house as they don’t have phones with every possible combination of parts. It can even be parts for a sub-assembly that’s doing it, where that supplier has used a variation of sub-suppliers for same part.
The pixelation issue, the only issue that im referring; was present in every 16 Pro i tested. I tested more than 20. Spain, Portugal, Ireland. (Apple Stores, Family)…
I tested also two 15PM , both updated to IOS 18. (Issue Present).
14PM series i cannot confirm.
And yes, as you described is Software fault (Pixelation), because the previous results with iOS 17 didn’t show that abnormalities (with the same exact device). - 15PM
And after the update the problem is immediately visible.
I confirmed that with 2 personal 15PM.
Independently of the manufacturing variations. if the problem appears only in one software version [IOS 17 versus 18] with the exact same device) it makes no sense to be hardware relatable.
But as you stated; it is caused by an unpolished software.
That was confirmed with the open case that i have with apple assistance.