Amazed to read this post...
I also have a Gigabyte Z390 Aorus mobo, Intel Core i7-9700k and run Mojave. And I have the exact same random usb freeze. (for a moment I thought me and you were the same person LOL)
For me it was rare and only happened after leaving my computer on for hours while not using it. But it just got worse since I'm using a usb Novation Launchpad MINI with Ableton Live. Now it freezes after 15 minutes.
Did you ever solve this problem? Do you know it's solved with newer Clover and/or newer macOS?
(I hesitate to update my hackintosh because I can't open my old music projects running 32bit plugins....)