The yellow color is because long-term use or frequent charging will lead to oxidation of the charging port, producing substances such as sulfide, and turning the surface of the charging grid yellow.
This may also be due to poor quality or improper use of the charger.
At the same time, the oxidation of the charging port will affect the speed of plugging, charging and battery life, so you should pay attention to the selection of high-quality chargers when charging and avoid frequent plugging, and unplug the charger in time after charging.
If the charging grid becomes too serious, you can protect the phone charging port by cleaning it, using special cleaners or cleaning it with professional tools.
The phone is on low battery mode
The charging display is yellow because the phone has turned on Low battery mode, which is an increased battery mode in which the phone temporarily reduces background activities such as downloads and email access until the phone is fully charged. The cell phone battery will change color according to the amount of power, generally green when fully charged, yellow when used to less than 20%, and red when used to less than 10%. If you want to turn off the low battery mode, you can go to Settings to find the battery, and then turn the low battery mode switch off, then the battery icon will return to normal
The reason why the iPhone battery icon turns yellow: When the low battery mode is turned on, the battery in the status bar will appear yellow.