iPhone 12 battery drain

Having battery drain issues on my iPhone 12 Pro Max on standby....no background app usage ...phone is always connected to WiFi no 5G..there is 15-20% battery drain overnight,,,even updating to iOS 14.3 doesn’t solve the issue..anyone got anything to share to optimise settings I’ve done everything on my part...or is it a wide spread problem with 12 series..posting both the images at 100% charge and @moring see the drain .