why is my I phone 12 mini battery draining

I bought last week an I phone Mini 12 and -although I turned of all battery draining features like refresh in background etc) the drains incredibly fast

I charged the phone yesterday at 22.00 (100%) and this morning at 07.00 (no use of the phone in the meanwhile, all apps closed etc) I had just of 50% remaining

my husbands I phone 8 only lost 5% of battery over the same period of time

what can I do (except for running to the apple store the claim a new battery or I do not know what ?

last remark : in the battery section it indicated my battery still has 100% of it's original condition (so it's not that I can find an answer there)