I ran this through an app called Coconut (also I have another one called "iMazing), this shows the true health of the battery. Launch day was an awesome 103-104%.
It took a slight hit after 15.0.1 (101%)
But another bigger hit after 15.0.2 update. So yeah, it shows "94-95%" now.
** YET...the phone itself shows 100% Battery Health under Battery settings
Also the battery % - top right corner - that has not been accurate also since this update. Will show 100% for 8-9 hours, but after rebooting it will then show 95-96%. Again...leave the phone idle for a few hours, % stuck at 95-96%, reboot will now show 92%.
I install updates though iTunes, no OTA to hopefully avoid issues. I don't know what this latest update did...or I (again) have a junk battery like I had w/ 12 Pro Max. (That health after 10 months dropped to a dismal 83%)
I just hope like I said the next update fixes this mess.
Edit - I downgraded to 15.0.1 yesterday, completely erased the phone and started over. The issue remains.