S21 cell standby draining battery

[mmtech]

I have been observing battery drain for some time and narrowed down to cell standby battery drain as Airplane mode doesn't drain battery. My phone is connected to cell tower that's it. No Internet, no background services, no wifi, stand by mode but still overnight battery drain is 10% in 8 hours. I just have dual physical sim and that was the reason buying Samsung instead of Apple. It looks like Samsung hardware is still not capable to handle cell reception which apple and old basic phones handled very well. Samsung still not improved after so many years and its a battery sucking machine.

Anyone else observed this issue and how to fix it ?

[mmtech]

Will try. But still 5% for single sim after all restrictions is high. For apple I never did any restrictions and with 1 sim battery drain was 1-2% overnight.

[mmtech]

Just did factory reset which is the last option. Will watch next few days to see it anything improves.

[mmtech]

Nothing improved. Same 10% battery drain in 7 hours night standby. Tried each and every option for power saving but battery keeps draining and its common across all Samsung phone. May be some have larger battery so it gets unnoticed but this is a serious and exclusive Samsung problem. 

[LXJ]

I am having the same problem with S21 (US model fully unlocked) now updated to Android 12.  I am outside of US and have one local sim card.  I noticed overnight drain of over 13% with all signals turned off except the cell connection.  The cell tower signal is not too weak, probably at 80%.  If I put the phone to airplane mode for the night, then it drains only 3%.

My wife has a S21 FE European model.  Her phone with the cell standby only drains about 3% over night.

Wonder what's going on.