It is not clear from the circuit diagram and data sheet why the current decreases when INPUT_PULLUP is selected.
By the way, why is pinMode(PIN_CHG, OUTPUT) used? If the charge controller sets the CHG terminal to LOW, it will cause a problem.
EDIT:
In my experiment, pinMode(CHG,INPUT) increased the current by 50uA. When pinMode() was not specified for the CHG pin, or when pinMode(CHG,INPUT_PULLUP) was specified, there was no increase in current.