It's a yellow mark that develops near the volume buttons, not an all-over yellow screen which is visible from day one.
Now I typically use my iPhones *heavily*, with a 'screen on' time of over 10 hours every single day. I get around 15-18 months out of an iPhone before this yellow blotch appears, and if I used my phone less then of course it would rack up a number of years before the yellow doom appeared. That doesn't excuse it though, and for two reasons. Firstly, I can use a laptop for many hours per day, for two or three years, and some other piece of hardware fails or I upgrade. Never does the yellow blotch appear on the LCD screen. Secondly, why does this yellow mark *always* appear near the volume buttons on my Apple screens? There must be some reason for this, such as heat damaging the screen or some other hardware issue causing the problem.
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Guaranteed for me. It has happened now to too many of my iPhones for it to be a one-off. I expect it to happen now and would actually be extremely surprised if it didn't.