Various Apple users have complained in recent weeks that the latest iOS update has caused their iPhones to turn off faster than normal.

You can see a sample of the complaints in this 13-page thread in the Apple forums (via News.com.au), but the gist of what's being said is that, after updating to iOS 10.1 (or iOS 10.1.1), certain iPhone models are shutting down as if they are devoid of battery, even while their battery indicators say they have about 30% juice left.

When these iPhones are plugged back in, they quickly jump back to that 30% mark.

Users at Hacker News and Reddit have cited similar issues, with some claiming the update has also resulted in rapid battery drain as well as miscalculations in Apple's Battery Usage table.

Anecdotally, four of my colleagues at Business Insider have also started suffering from the issue after updating to iOS 10.1.1, which was released in late October.

The conditions of the issue seem to vary. The complaints suggest the point of shutdown could be slightly higher or lower than 30% and that the iPhone 6s, the iPhone 6s Plus, the iPhone 6, and the iPhone 5s (at least) have been affected.

Earlier in November, Apple announced a free battery-replacement program for users experiencing “unexpected shutdown issues" — suggesting the problem is hardware-related — but it said the problem affected only "a very small number of iPhone 6s devices" manufactured from September to October 2015.

As a result, only a select number of devices are eligible to receive a new battery. (Apple recently added a tool to its webpage that lets you know if you fall in that camp.) With more than just iPhone 6s devices seeming to suffer from unexpected shutdowns, though, there's a chance that some iPhone owners are stuck with a faulty battery, with no apparent fix for the time being. This is the case with my aforementioned colleagues.

It's worth remembering that grumbles over iPhone battery issues are nothing new. An endless array of factors could cause a phone's battery to behave strangely, from buggy apps to hardware stress to basic user neglect. Some users have reported similar unexpected shutdown issues with iOS 8 and iOS 9 updates in the past, too, so again, we can't say if iOS itself is specifically at fault.

Still, while most iPhone owners don't appear to be affected, iOS 10 has not been immune to bugs since its public release in September, and there at least seems to be some smoke worth noting.

Apple did not respond to multiple requests for comment.