You can then connect many different types of Thunderbolt and USB-C devices to the two ‘downstream’ Thunderbolt/USB-C ports on the back of the dock.  The type of functionality provided by the two ports on the back of the dock is ultimately determined by the capabilities of the host computer.

To put that another way, if the host computer has Thunderbolt 4 technology built-in, then both ports on the back of the dock will function as Thunderbolt 4 ports.  

If the host computer has USB-C technology built-in, then both ports on the back of the dock will function as USB-C ports.

If the host computer has Thunderbolt 3 technology built-in, then both ports on the back of the dock will function as Thunderbolt 3 ports***

*** Please note, the specifications of a Thunderbolt 3 host system can have an impact on the level of functionality of the dock’s downstream ports ***

When a Thunderbolt 3 host system that has:

A. An Intel Titan Ridge Thunderbolt host controller
B. A DCH variant of the Thunderbolt host controller driver higher than version 1.41.613.1 installed
C. An internal Thunderbolt NVM firmware version of 41 or higher

Is connected to the dock, then both downstream ports will function as Thunderbolt 3 ports.

When a Thunderbolt 3 host system that has:

A. An Intel Alpine Ridge Thunderbolt host controller
B. A DCH variant of the Thunderbolt host controller driver installed

Is connected to the dock, then one downstream port will function as a Thunderbolt 3 port, and the other port will function as a USB Type-C port.