If there are battery drain issues in sleep mode,
in order for us to verify, please kindly follow the steps below and show us the screenshots.
1) Charge the phone to 100% before going to bed > remove the charger > Clear all apps in recent app list > turn off screen > the next morning before using the phone, please screenshot the two pages:
a) Settings > Battery
b) Settings > Battery > ""Advanced battery usage"" (tap the battery icon to access)