Use Low Power Mode to save battery life on your iPhone or iPad - Apple Support (HK)
iApplebytes confirms iOS 13.5.1 has a worse battery life, geekbench 5 battery test is a intensive test. On my iPhone 11 i got around 9-10hours of screen on usage and on geekbench
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How to Fix Bad iOS 13 Battery Life
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How to Fix iOS 16.3.1 Battery Drain Issue on Your iPhone: 10 Useful Tips | TechRushi
iOS 13.6 Battery Drain Fix for your iPhone
iPhone users complain iOS 16 is a battery drain, has other issues
How to Fix Bad iOS 13 Battery Life
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New Apple iOS 13 is KILLING batteries as iPhone owners find battery life drains quickly | Daily Mail Online
Apple no longer signs iOS 13.7, blocking downgrades from iOS 14 - 9to5Mac
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Apple's iOS 13.3.1 Update Reportedly Drains iPhone Battery Fast
iOS 15.3.1 Battery Drain Issue Fix || how to fix iOS 15.3.1 battery problem - YouTube