I got a new iPhone eight from the Apple store about a month ago. out of the box it came with iOS 12.4.1. after a couple weeks I decided to update to iOS 13.3.1. now my battery drains about twice as fast as it did with iOS 12.4.1. I went into settings and checked my battery health and it was at 100%. I checked my battery usage by app and couldn't find an obvious culprit for the problem. That made me start to think that voiceover could actually be what is draining my battery so much. now I'm having to turn on mono audio to save battery while using the built-in speakers on my phone and even with mono audio on the battery still drains faster than when using stereo audio in iOS 12.4.1. I have noticed that when I use voiceover a lot the back of my phone is warm. i let a representative from Apple Accessibility know about the issue, and he says that he is aware of iOS 13 in general draining the battery. on a normal day, my voiceover volume is set to 100% and my device volume is set to 50%. my screen curtain is almost always on. even at lower device volume the battery still drains much quicker than normal. I hope that Apple fixes this problem soon. edit: when I am at home I am using Wi-Fi calling with airplane mode on and The battery is draining faster than it did when I used the cellular network in iOS 12.4.1.