iphone SE3 loses charge after fully charging to 100% and on the charger
This is really weird. My iphone SE3 is only 2 1/2 months old, but it has started doing this oddball discharging while on the charger.
For example, my phone had been on the charger for several hours yesterday evening while I was using it as a hotspot. I turned off the hotspot and went to sleep with the phone showing it was 100% charged.
This morning my phone showed 66% charged while still connected to the charger (genuine Apple). The battery icon showed the lightning bolt indicating it was still connected to the charger. I looked at the battery health in Settings, it said my battery is 100% good, and charge history showed the charge declining from 100% down to 66% from around midnight until about 10 am.
I unplugged the lightning cord blew in the iphone socket, and plugged it back in. It charged back up to 100% in the normal amount of time.
Attached are screenshots showing what the iphone system>battery and program usage shows.
Is my iphone defective? Am I missing something? I'm coming up on 90 days and want to get it fixed/replaced while under warranty if this means the phone is bad.