On the Huawei P20 Pro there is an option that automatically changes the background lock screen when the device switches to standby mode. This means you'll see a new wallpaper or cover on the lock screen every time you turn on the phone screen.
If you do not want to use this feature, you can deactivate this option in the Android settings as follows:
Update Huawei P20 Pro Cover for the lock screen
1. On the Huawei P20 Pro, open the Android settings
2. Scroll down to "Security and Privacy" in the menu and select the following entry:
Here you will find the option "Update cover" - Deactivate this function with the controller - Done!
The background image on the Huawei P20 Pro lock screen no longer changes automatically.