New Iphone 14 battery decreases super fast

I just bought an refurbished Iphone 14 in perfect condition with 100% battery health. The battery is decreasing really fast though. I turned off background app refresh for almost all apps as well as location tracking and also make sure to never put my brightness too high. Yet, spending 6 minutes on instagram (using wifi and not having any other apps running in the back) costs me 1%. I'm kind of worried of how bad it will be once the battery health decreases... Should i send my phone back or is this actually normal??