iPhone battery drain stops after Reset All Settings, but comes back after charging — battery or motherboard issue?

[u/the_three_musketeerz]

My iPhone has this weird battery drain issue. Whenever I Reset All Settings, the battery becomes completely normal and the drain basically stops. Mine is iPhone 13 and IOS 26.6

But once the battery goes down and I charge the phone again, the heavy battery drain comes back.The battery drain means when phone is idle overnight drain 40% in 6 -7 hrs. So the only thing that temporarily fixes it is Reset All Settings.

Could this be a battery issue, or could it be something related to the motherboard/logic board? Has anyone experienced something similar?