iPhone 8 Battery after iOS 16 update.

After the update of 16.0.2 in my iPhone 8, the battery is draining too much fast, like 4% drop in 2 minutes. I was playing Battlegrounds mobile India when my battery level was about 71% then after just 10 minutes, it was only 10% left. That never happened before iOS 16.0.2 update. My battery health is 84% and supporting normal peak performance.

And there's more, When I restart my phone the battery level gets increasing. I restarted my phone when it was on 12% battery, after restart it was 34%. I don't know if it is a bug or something but it happens every time when i restart my phone.