Op posted to 8+ subboard so, guessing not an X?
Bigger question is: where are you getting screen time info? And even then, times are YMMV. Cellular vs wifi access? Strong wifi vs weak (eg. Need to use an extender for back of my home's property [patio] vs AC router inside)? Weak cell coverage? Background apps (eg. Playing music/podcasts)? Big on getting notifications? Using a mapping app? Bluetooth devices? GPS apps running? And so on.
Imo, everyone's usage is different, so, not worth getting wound around the axle comparing others' usage. If happy, be happy. Batteries wear down, particularly if going through lots of charge cycles.
My 1yo 8, dropped about 40% over 8+ hrs with podcasts, web, mail, and Gas Buddy app. Coconut Battery says 94% battery health.