I would try running the playfield camera only and unplug the others. Does it still happen? Do you have plenty of auxiliary light on the game? Does the camera behave differently if on default settings instead of custom?

I’ve never seen this issue before, but these are the first things I’d try.

I used to sometimes have this issue when the playfield camera is too close to the game.

My theory is that I am overloading the USB bus with data because a higher percentage of the image is changing at any one time.

So I've fixed it by putting the overhead on the USB 3 port through a USB 3 hub along with my USB 3 capture device. The other 2 cameras go in the USB 2 ports. Then setting the overhead camera higher and using a crop filter. More overhead lighting may have also helped because the inserts would light up a smaller area.

After making these adjustments the problem went away.

You could be getting EMF interference which is corrupting the USB data stream. Those distortion areas align to what I would guess is the compression blocks that make up the image. You could try a shielded USB cable that uses a ferrite core. I've seen similar problems with unshielded cables in a manufacturing environment that a shielded cable has resolved.

Shielded vs unshielded is a good point too. I’ve only seen this effect streams that use usb hubs extended by Ethernet, but definitely something to try.

If you’re using a hub too, they can cause issues if you have multiple web cams hooked into one hub.