I bought this hub (model number A8380) which has two HDMI ports, and the product description says that it supports a single 4k display at 60Hz (or two 4k displays @ 30Hz)
I confirmed that the hub does indeed support a 4k 60Hz display on Windows. However on Linux, it only works at 30Hz. I found a blog that explains some of the technical details about USB-C hubs, DisplayPort and 4k displays. The blog says that USB-C (USB 3.2 gen 1) hubs only support 30Hz 4k HDMI displays. The exception is DisplayPort 1.4 which neither my monitor or laptop support.
So, my question is: How does this particular hub support 4k @ 60Hz? The blog linked above suggests that some hubs do this by using DisplayLink which uses a custom USB protocol instead of DIsplayPort. I had a look at the USB devices that appear when plugging in the hub, and nothing mentions DisplayLink. The answer might help me figure out how to get it working fully on Linux.