I have done a clean install of ipsw to my iPhone 11 Pro through iTunes (which has 100% battery health) and also I did the same procedureto my iPad 6th. I didn’t press restore from back up so I chose set up as new. I only opened iCloud switches in order to get back my photos which cost me to loose my calls but I don’t mind. Weeks have passed and I figured out that I have battery drain in both devices. I thought that it could be a normal behaviour in order to complete the index procedure. But now I am in the third week and I my battery doesn’t last. I have 0 widget in my homescreen in both device. I think iOS 14.1 was performing better in battery. It was pretty solid and I used to charge my iPhone once every 48 hours and now I charge it once every 24 hours. I have Bluetooth off and I have 3G opened and closed 4g. I wish I had the same battery as in iOS 14.1.