The hub doesn’t have a negotiation chip to set the voltage correctly. It is likely presenting as a bus hub. Like if you do $ lsusb on Linux, you’ll see the hub and whatever is connected. That hub may be integrated into other chips or it may be stand alone as a peripheral somewhere on the board. It is basically like a digital capable splitter for the bus. It is only concerned with the data. The power is likely just passed through. For USB-C PD, it would need some complex additional circuitry to negotiate, convert voltages and do current limiting. The way the pins can be inverted by flipping the connector makes it logically complicated.