iphone 14 battery life dropping really fast

hi everyone. so i got an iphone 14 back in january and the battery life has been dropping REALLY fast over the past month which is quite concerning to me. so basically over the past month, i dropped from 97% to 94%. i was at 98% capacity between march and august and i’ve read that the capacity dropping this quick is pretty normal because it’s trying to catch up to what its actually meant to be and also because of ios 18, seeing as i had the capacity at 98 for several months

can someone let me know if this is actually normal? for your capacity to drop this quick? and also, how much does a battery replacement cost? thanks guys!