I've got a weird issue on my iPhone 8 using iOS 15.4.1. that just started yesterday (Apr17). Randomly when using my phone, it will reset without warning. It seems to happen whenever an app attempts to use Location Services (as in the Location Services arrow will show in the upper bar). When that happens, the phone resets and will go into an endless reset cycle until I plug the phone into a power cord. It does not matter how much battery power I have just before it resets (could be 100%, could be 60%, doesn't matter).
While the phone is plugged in to power and boots back up, it shows very little power currently available on the battery (ex 8% or 9%). It then rapidly increases its charge (as I type, this happened, and it went from 8% battery to 60% in just a couple of minutes).
This has happened multiple times in the past two days. I just updated to 15.4.1 this past Thurs or Fri. My phone says that Battery Health is at 92% Max Capacity (phone is around 2 years old).
While I suppose my battery might be prematurely dying, it feels like maybe this latest iOS version might have something to do with these weird glitches. Not sure if anyone else has had this issue.