Massive battery drain with iOS 13.3.1, iPhone 7+ : r/ios
iOS 13.4 Battery Life Drain Comparison Against iOS 13.3.1 | Redmond Pie
iOS 13.4 iOS 13.3.1. Battery life test. - GADGETALERTS.IN
Anyone else having battery drain issues? I have an iPhone 7 Plus running iOS 13.3.1 and I've randomly lost 20% battery in 5 mins. New OEM battery too. : r/ios
Battery performance comparison on iOS 13 and iOS 14
Apple no longer signs iOS 13.7, blocking downgrades from iOS 14 - 9to5Mac