Cause:

Wake device or Raise to wake is enabled by default when you use Face Unlock. In this case, the screen wakes up whenever you pick up the phone. As a result, the phone battery drains quickly.

Solution:

Open Settings, search for and access Wake device or Raise to wake, and disable it to reduce unnecessary screen power consumption. To use Face Unlock, press the Power button to turn on the screen and initiate face recognition.

If the issue persists, back up your data and take your device and proof of purchase to an authorized Huawei Customer Service Center for assistance.