iPhone 7 display

Hello,

I have a question about my iphone 7 display.

Recently I purchased a used phone and I’m worried that my display was already replaced.

I went to a few local stores to compare my iphone with other iphones on display and I noticed that the ones in the store have different colours and is somewhat darker and more yellow. Iphone 8 on the other hand had a display very similar to mine.

So is it normal that every iPhone 7 is different?

I’m happy with my display its bright and vivid just after comparing im not really sure...