

This is a designed feature of your phone. For example, the screen brightness automatically changes when using apps such as WeChat, Browser, Contacts, and Messaging, even if automatic brightness adjustment is disabled.

(The screen brightness will decrease if the ambient light sensor is covered.) If you want the screen brightness to stay the same, open Settings, search for and touch Display & brightness/ Brightness, disable Automatic, then adjust the screen brightness to the desired level manually. You may have enabled Automatic on the brightness settings screen, resulting in the screen brightness automatically changing to a suitable level based on the environmental lighting conditions detected by the ambient light sensor on the top of the phone.The screen brightness changes when the user opens, uses, or closes an app
