My Ultra 21 (Exynos) STILL loses 25% battery overnight (8h) when VoLTE is activated.
I have 5G disabled, many apps put to sleep and running the latest Software (G998BXXS2AUBB).
Without VoLTE it is only draining 4-5% in 8hours.
I didn't have this kind of battery drain with VoLTE enabled on my S20.
I have s21 exynos and have same problem, tried factory reset, cleared cache after every update (and i had 3-4 updates since i've got mine) and now i'm on latest AUBB but battery life with lte on is horrible. It barely lasts one day with 3 hours of sot.
It should not be an exynos only problem because also snaps are experiencing them.
However it is a restricted problem, my guess is that it is due to bad silicon lottery
I cleared the cache after the first updates. Not after the last one. Honestly, i don't think that's the solution.
Without VoLTE, battery life is 2d with 6-8h sot. With VoLTE around 22hours with 4h sot.
Samsung should make some statement and say they are aware about problem whatever it is. When you contact customer support first thing they say to you is that you do factory reset. And that's not so good experience, I transfered all data from my old phone and i have to do the factory reset, just because samsung won't acknowledge the problem. My last samsung before this was galaxy S2 and if this issue won't be resloved, S21 will be my last samsung ever. I could get over it with midrange phone for 300$, but this is freaking flagship.