Apple has released iOS and iPadOS 15.4.1, an update that fixes some accessibility bugs, improves security, and fixes a battery drain bug that plagued some people’s phones and iPads after they updated to iOS 15.4.
It’s unclear how widespread the issue was (nobody on The Verge’s staff reported notable battery problems), but earlier this month, the Apple Support Twitter account told customers complaining about battery drain that it was “normal for your apps and features to need to adjust up to 48 hours after an update.” Still, over two weeks after the update was released, it’s not hard to find recent posts reporting poor battery life. Hopefully, though, the update will solve those — iOS 15.4 brings the really handy update of being able to use Face ID while wearing a mask, so it’d be a shame if people didn’t want to update for fear of battery issues.
Thanks for reaching out! We'll be happy to help. It's normal for your apps and features to need to adjust up to 48 hours after an update.
Let's have you reach out to us in a DM if this is still an issue after that time so we can help you look into this further.
— Apple Support (@AppleSupport) March 19, 2022
Even if your battery has been fine, it may still be worth updating reasonably soon. Apple says that iOS 15.4.1 (and macOS Monterey 12.3.1, also released today) contain security fixes for issues that Apple says could’ve been exploited in the wild. Unfortunately, this sort of warning has become pretty routine in Apple’s security bulletins — while indefinitely putting off updates has never been a great idea, it seems it’s more important than ever to make sure your devices are running the latest version of their OS.
To update your iPhone, go to Settings > General > Software Update. To update your Mac, go to System Preferences > Software Update.
Source: https://www.theverge.com/2022/3/31/23005192/apple-iphone-ios-ipad-battery-drain-bug-15-4-1-update-security