Such is the case for iOS 11.1.1, which Apple rolled out late last week to fix the bug that was turning the capital letter "I" into a unusual symbol.
Reportedly, the iOS YouTube app is consuming excessive battery power, even when it's closed and running in the background.
A new bug in the YouTube for iOS app is causing significant battery drainage, and in certain cases, device overheating for some users. Some used Twitter to let Apple know that once they have installed the newest iOS update, they started to experience severe life battery issues.
An iPhone should not run hot whilst simply playing a video, so it certainly seems like there is a bug in either iOS 11 or the YouTube app that needs to be addressed. It's not known yet what is causing the issue, but YouTube have said that they are "actively working to fix this". As a result, many users have elected to uninstall the app entirely and resort to watching YouTube videos in Safari, an annoying workaround to help preserve battery life.
The iTunes listing for YouTube shows that an update for the app was released today, but it doesn't appear to contain that bug fix. Without a YouTube Red subscription, you can't run background playback.
Hopefully YouTube are working away on this now, and we'll see an update in the coming days which will put an end to this problem. Depending on whose complaint you listen to, the battery goes down 20% in fifteen minutes to half an hour of watching video, which, by all counts, sounds pretty bad.