Yeah,me too facing this problem.
M Also facing this problem . Please Revert
Please try clear the cache of the Battery Protection app.
It's a system app, so:
Settings > Apps & notifications > App info > Menu dots > Show system > Battery protection > Storage > Clear cache.
App info also has an option to reset all apps, but note the warning if you adjusted a lot of preferences (and I'm not sure if it clears all the app caches properly).
FWIW I get ~5 hours of photo/video record/edit/upload continuous use, or ~5 days standby, with built-in apps and standard settings everywhere.
Standby improved a couple of days since Oreo for me, when the phone is static and in good 4G mobile coverage.
If you already tried clear the battery protection app cache, then the next troubleshooting step is remove the SD memory card (if any) and do a factory 'hard' reset.
Add your Google account after the factory reset, do not insert a SD memory card, do not add any apps, but let it update the built-in apps to their latest version.
Recharge the phone, unplug, and let it sit overnight without use.
Observe the battery drain in the morning.
It only takes one Android 8 incompatible or poorly written app, or a poor quality or defective SD memory card to drain the battery.
If the battery drain is still excessive after a factory reset with pre-installed apps only, and with default settings everywhere, then claim the warranty via the place of purchase or a Care Point.