What's wrong with Nubian mobile phone battery showing yellow?

When the battery of the mobile phone is lower than 30% and the power saving mode in the mobile phone settings is turned on, the mobile phone will reduce the power consumption and enter the power saving mode, and the battery display will turn yellow.

You can enter the phone settings-other system settings-battery-power saving mode and turn it off.

Generally, when the battery of a mobile phone is low, it will automatically pop up. It can be noted whether it is set to the power saving mode.