Hmmmmmmmm...
https://forums.macrumors.com/threads/is-there-even-display-on-iphone7.2004586/
https://forums.macrumors.com/threads/here-we-go-again-iphone-7-terrible-screen-quality.2008196/
Yup more and more people are noticing these "picture perfect" screens from apple.
You two options.
1. Learn to live with it.
2. Start returning phones until you can find one you can live with. But it could be a lengthy process that involves multiple replacements (getting one worse or different/same problem as last one) and you still end up without your problem fully solved. Take it from me I went through 8. (Cough) yes 8 iPhone 6's till I finally gave up. I had screen uniformity problems on all of them. Some worse than others. And some with different defects. Clicking lose screens, buttons, cameras, yellowing dark patches on the screen you name it. The QC checks on the last 3 years of these phones is lower since they make so many of them and the majority of people don't care or notice some things.
My first and only JB 7 has a pinkish tinge in the upper left side and a dimmer yellowish tinge in the bottom that you can see on white screens. But based off of experience I think I'm just going to live with this one!!!! The battery life is awesome and I hear no hissing and everything else seems to work ok. But then gain every time I use it my eyes are drawn to the un-even parts of the screen and I have to remind myself that nothing is perfect and it's very hard to find an edge lit LCD with perfect uniformity.
Hope this helps and I hope we get OLED next year!!