I've been following this and many other threads on the issue, as my iPhone 6s is also affected. I am sad to report that none of the solutions seemed to work. The problem appeared after upgrading from 14.2 to 14.3. Upgrade to 14.4 RC has not helped either. Installing a new battery made 0 difference. I am in the position where I must charge the phone semi permanently to be able to use it for a bit of email checking. Anything more than that the battery is dead within 10 minutes. The phone is warm/hot even while cycling around at 0°C I had a good experience with the phone for the past 5,5 years, but now am contemplating changing ecosystems. Otherwise my options are: Either buying a new phone for 1000+€ or Buying refurbished/used older model for 400+€ in which case I will be having the same problems in a couple of years seeing as Apple is so big on planned obsolesence. It might be cheaper to pay the fines for the planned obsolsence cases but in the long run I hope consumers will not put up with this. At the very least I will not be giving you my hard earned money again.