After the update im losing 20% during the night, already reinstalled the system with odin and disabled lots of stuff and nothing works, I dont even use bluetooth nor wifi during night.
What I noticed is that (S20 FE 4g) on the one ui 3 it seems like the phone is trying hard to find a connection and using too much 4g, so when I changed to 3g/2g my battery lasts more than one day without saving mode and with 120hz
I did it for testing and it wasted only 3% ! I used 2 SIMs with 4g enable, the solution I found was use on the 3g/2g mode while using WiFi. Wifi off and on 3g it still waste only 3% , I'm getting one day and a half with light usage its like a new pho...