iPhone 12 Pro Max randomly restarts and has volume issues after iOS 27 update

I updated my iphone 12 pro max to iOS 27 and now it is randomly restarting. It was starting this behavior while still using iOS 26, but it was only two times total. Under iOS 27, it seems to be every hour or sometimes multiple times an hour.

I have 30 GB free on the phone. The battery health is at 50%, so it might be the battery failing, but I can't really aford to replace it right now. I live between chargers and I am pretty OK with that. The following is an info dump. Sorry.

There isn't a particular app that causing the restarts, sometimes it is Tik-Tok, or a game, or mail, or texting. Just now when I was using the phone, the battery said 45% then it just shut off. Completely without warning. I had to plug it into a wall charger to get it to start and when it did, it when to a recovery screen that I have honestly never seen before. The battery percent was only 5% and climbing. I tried a recovery or something but it wouldn't do anything. I finally got it to restart, battery percent was 25% before restarting the phone, and was 60% as soon as my home screen came on. There definetly seems to be a battery glitch but I don't know if it is purely software or if it is a hardware issue causing a software glitch. I wanted the iphone to re-analyze and re-calibrate the battery but there doesn't seem to be a procedure for that to happen automatically.

As well there is a volume issue with the phone. I will be listening to a tik-tok and at the start of the vid the volume will be super quiet but gradually increase over the video until it is max volume, but it will remain at max volume when the vid repeats. As well if the vid starts quiet, I pause it for a minute and then let it run then it will be at max volume again. It is confusing and changing settings doesn't seem to help. When I am using a blue-tooth headset it doesn't happen. It feels like a volume levelling glitch has caused it to be super wonky but seen in iOS 26 and 27.

I don't think the two issues are related, but who knows. Right now I think the battery is dieing and that is causing the iOS to volume limit, even though the Displayed battery percent is above 50%.

Any help, or guidance would be great. Thanks!