Battery will only charge when phone is switched off

My iPhone 11 no longer charges when switched on, the battery icon is never green , but permanently black or white depending on the background, even when a perfect charging cable is connected.

I have to switch it off to charge it; the battery also seems to drain quite quickly. It’s running at 82% of efficiency after almost two years. Another odd thing is that if the phone is switched off without the charger in, and the charger is connected, the phone switches on automatically. I have to plug the cable in and then switch off.

Anyone have any similar experiences or advice?