Over the weekend I noticed my phone battery was draining much much faster than usual despite not using the device as much. I haven't updated the iOS in over a month (currently on 11.1.2) and haven't updated or installed any apps in over a week. Usage has been the same if not less than usual.
Normally, I'd leave it off the charger overnight and it would lose about 5-10%. Only now it would lose about 50% or more overnight. Normally, I can get through a whole day and use 50-60% without any additional charging. Now, I've barely gotten through half a day and down to 30%.
Performance wise, my phone hasn't slowed down. I can use the apps without any noticeable lagging. What the flip is wrong with my phone?!