Basically, VDDD is used as output voltage pin but VDDD can use input pin to provide power to analog circuit.
I cannot imagine what case we use VDDD for input pin in.
So please let me know all of the case.
If you are using VDDD as input, the power input will for core power of CCG3. If there are no external power source on VDDD, VDDD will working as output power with 3.3V. But the output of VDDD cannot use to drive other external chips only for VDDIO use is fine.