My RPi screen resolution is lower when I power it from a mobile charger than when I power it from a power supply. When I use the power supply it gives a different (higher) resolution.
I checked the voltage of the mobile charger I'm using and it doesn't go below 5V. (I checked it while the RPi was on and also during boot). I've also tried limiting the current of the power supply to 1A, and still the RPi gives the high resolution.
I'm using a RPi 3, and Raspbian with pixel. The mobile charger is rated at 5V, 2A.
This is very confusing! What could be the problem?