As I've said, the TINY UNREADABLE fonts problem HAS BEEN FIXED. You with 4K monitor are all reporting a whole completely different issue, which is NOT tiny unreadable fonts, but just fonts as smaller as they used to be even, again, I have no frame of reference since I have a 1440p monitor, so I don't know *exactly* how they looked like before.
I'll try to explain it again: the bug that has been fixed is the one that, when you open the menu the first time, the fonts where microscopic, NOT as in your screenshot, but way, way smaller. And as soon as you clicked on the menu border, they fixed themselves to their normal size. THIS and only THIS is the bug that HAS BEEN FIXED in 3.4.4.
You are seeing something different, and I suspect one or more updated files might have not reached your local cloudflare node, even if the manifest.json has (so quoting the manifest.json is not very useful, it only show you at least *tried* to update).
Can you check the size of these two files ?
\Addon Manager\fsdreamteam-gsx-pro\html_ui\InGamePanels\FSDT_GSX_Panel\FSDT_GSX_Panel.css (should be 2860 bytes)
\Addon Manager\fsdreamteam-gsx-pro\html_ui\InGamePanels\FSDT_GSX_Panel\FSDT_GSX_Panel.html (should be 3994 bytes)
If the copy you have has a different size, you don't have the latest version we have online now so, just try again an update CHECK, I'm sure the update files must reach your cloudflare node, I also forced a cache retrigger, in case cloudflare didn't take it.