battery discharge differential in iPhone 7

i have two iphone 7's. same model and memory capacity. i noticed one was draining it's battery faster than the other, so i ran some comparisons.
i made sure each phone was running one app and the background settings are the same. i know i should have probably timed them but didn't because i didn't have time to really monitor them. what i can say is that when the first phone hits the 20% warning, the other phone was always between 40% and 45%.
the only differences that i can point to are.....

1) the 20% phone is running IOS 15.2, the 40%+ phone is running IOS 14.8.1.

2) both batteries are original and are close to 85% health

3) the 20% phone battery has 774 charge cycles, the 40%+ phone has 380 charge cycles

so my questions are, can 15.2 or a higher charge cycle count be responsible for a faster battery discharge? or is there some place else where should be looking?
thanks