One of the things that it could be related to is network or the at&t carrier.
Call is what drains the battery the most, safari second.
Yesterday I got a notification about carrier update, I just pressed ok. Not sure if this will help but I believe that are other things related for the battery to drain faster with the IOS13.1.3.
I also called apple and they run a remote test on my phone, everything was ok according to the three tests they run.
They suggested me to do a restore which I have done weeks ago but i didn’t fix anything.
I look at the battery chart and activities and it looks fine, I don’t see anything abnormal.
Still not sure what else to do.
Close to tape a battery pack on the back of this phone, really.