ADC pin current consumption
The pin of the ADC will not take that current unless the voltage on that pin is taken above the supply rail to the chip. Your potential divider ensures it doesn't do that in two ways. Firstly it is a potential divider and therefore will reduce the real input's voltage to a lower level and secondly the impedance of the resistor means the raw input voltage would have to be ridiculously high to generate 25mA.