So about my usage on my 12 Mini, I use my phone without anything turned on, except mobile data. If I need GPS, BT, Wifi etc. I turn it on and off again when not used anymore. No background sync, no push, no covid, no nothing because I don't need and use it, and only a few notifications turned on.
All nights, besides the first night, in complete airplane mode I lost 0% over night which is perfect actually.
One night NO Airplane mode but only mobile data turned on, 2-3 bars LTE, and receiving around 6 notifications from an air quality device app I lost 27% which is ridiculous!
One night in Airplane Mode but with 5GHZ Wifi turned on, Router not far away, and 0 notifications I lost 8% which I think is bad too.
So something is definitely going on in the background but I have no idea what it is as battery usage shows nothing, maximum 1min lock screen usage in an hour.
8% in one night with only Wifi turned on and 0 notifications is bad. And 0% lost during a night in airplane mode is the opposite, perfect!!!