My samsung galaxy s8 battery finish in 4-6 hours after 100% charge. I tried everything like. Reboot, device mantainace clear cache , scan, Apps battery save mode and all that. But still my s8 has same issue . Google play service using battery 81% I don't know why. Very disappointed after paying £599 I have to use phone with this problem. I'm sure fast charging is not a solution.
My first piece of advice is to put the phone in Safe Mode which will turn off all the downloaded apps and leaves the stock ones alone which can then help you see if this is because of a rogue app if the issue stops.
If it does not stop then I'd suggest to create a back up and factory reset.
If no help then either take the phone back to source or a Samsung Experience Store or Samsung Service Centre location can run a diagnostic on the phone.
Current Phone ~
Samsung Note 20 Ultra 5G SM-9820 _256Gb SnapDragon 865+
Samsung One Ui 2.5/ Android 10.