iPhone screen dimmer on iOS 14

Hi there, I'm asking if this is a hardware or software thing, so I have 2 iPhones (iPhone 8 iOS 14.8, iPhone 6s iOS 13.3.1) and I noticed that when I'm on minimum brightness the 6s is brighter than the 8. Is this a software thing? Where iOS 14 allows the screen to get dimmer? Or is the iPhone 8 screen more worn, I got it used so I don't know.

Here are some photos for reference: