Okay, so I did a bit of research and this keeb does indeed have ESD protection.

Here is a shot of the PCb where the protection IC is located: https://i.ibb.co/7KQQ7gZ/IMG-5526.jpg

In that shot, you can see the JST connector and to it's right, a small IC labeled UL26. That IC is the ESD protection. Here is it's datasheet: https://www.st.com/resource/en/datasheet/usblc6-2.pdf

Here is a shot of the daughterboard: https://i.ibb.co/2vnQqjJ/IMG-5516.jpg

As you can see, there is no UL26 located on the daughterboard. There is a part labeled A7 that appears to be grounded (?) to the case via the db's screwhole. I also speculate that the USB hole in the case is too tight and perhaps the USB connector is hitting the case and that's how the ESD is making it through. The main PCB should be well isolated with the gaskets in use as well as the thin isolation sheet in the case.

Perhaps the fault is with the data lines? Doesn't seem to be much if any protection on those lines and maybe that's how ESD is affecting these boards... but I honestly don't know enough about this and I am just hoping that what I provided can offer some insight into the situation.