We are sorry to hear that you are having this issue.
What'syour phone’s firmware version (Settings > About phone> Build number)Are you talking about battery drains in standby mode or in use?
If you think that there’s battery draining in standby mode, please charge your phone to full before going to sleep, and leave it unused and unplugged overnight. Please capture 2 screenshots as below on the next morning before you use your phone and tell me how many percentages of power the phone has consumed overnight:
1. Battery: settings> Battery (Device usage since full charge)
2. Battery usage: settings> Battery> click the three dots > battery usage>show app usage