Yes, Dick, I've seen others on various forums have this same USB Device Manager problem, but at different times. It's puzzling. But it can't be a coincidence that I found exactly the same unwanted setting change on all 3 Windows 10 Pro PCs at the same time.

Indeed it probably does relate to specific KBs. Some research into this might be useful. But not by me, because I do not wish to explore just what pathologies continue to fester in Microsoft's, um, minds.