iOS 16 is freezing my iPhone 8 plus

Hello, everyone!

I had iOS 15 (I believe it was 15.7) until this morning, when I decided to update to iOS 16.1.2 on my iPhone 8 Plus.

In 8 hours I had 5 freezes: the phone doesn’t respond to any input, after several minutes the screen turns black with the rotating circle in the middle (which is not rotating, it’s just sitting there; please see the uploaded image) and afterwards it restarts with the apple logo on the white screen.

This is happening randomly and the apple support guy told me it might be because I have the battery health at 75% and he recommended changing it. The phone was working fine on iOS 15 and I have heard of the scandal regarding batterygate, so I don’t buy it. Also, the battery drains like crazy with the new iOS

However, if my iPhone doesn’t support iOS 16 (which then apple shouldn’t market it as supported by iPhone 8 Plus), I just want to go back to iOS 15. The Apple guy told me it’s impossible, but I understood it isn’t.

Therefore, can you please help me with the steps that I have to follow in order to downgrade? Or do you have other ideas to make the iPhone work on iOS 16?

Thank you!