Is this MST Hub VESA certified?
I don’t think VESA certifies MST hubs.
The CSV-7300 uses one of the Synaptics MST Hub chips (probably the VMM5330 or similar) which is used in many DisplayPort 1.4 MST Hubs.
Some early DisplayPort 1.4 MST Hubs did not have the firmware to support DSC. Since the CSV-7300 advertises DSC support, one can assume that it has the latest firmware (or at least a version that has DSC support).