Many consumers noted that their iPhones had poorer battery life when running the prior iOS version shortly after Apple published the iOS 15.4 update. This isn’t the first time that an iOS upgrade has caused problems.
The issue has been confirmed by the Apple Support account on Twitter. Apple responded to iOS 15.4 battery drain issue and said it took 48 hours for iPhone apps and functions to adapt to the latest iOS version. Therefore, power consumption will be reduced.
After 48 hours, Apple recommends people to wait patiently. Users can restart the machine after this time period to continue supporting this process for applications. Customers can contact the Apple Store for assistance if the battery drain problem continues to occur.