Understood. The connectors are USB C but I believe the actual USB version is USB 2.0 . At least according to Sweetwater. I could find no reference confirming the protocol in any of the Presonus documentation released so far.
To the best of my knowledge the new Quantum HD are USB 2 protocol interfaces while the older models were Thunderbolt.
It will be interesting to see real world latency results with the Quantum HD.