Constant input to A0 pin from HX711 amplifier and load cell

Why is the VDD pin of the HX711 connected to 3.3volt.
That's if you use a 3.3volt Arduino.

A Mega is a 5volt Arduino, so both VCC and VDD go to the 5volt pin.
It shouldn't make a difference, but VDD to 5volt could make data more reliable.
Leo..