New
#11
I got a tech to respond in the Microsoft forums. After going back and forth with him a bit, it turns out a lot of applications use the primary display as their scaling baseline. They then re-scale according to the scaling percentage on whatever monitor they happen to be on. So if I made one of my HD monitors (which have scaling at 100%) the primary display, then Chrome would look fuzzy on my UHD display, which is using 150%. I tried it and sure enough, that's what happened. Basically it's exactly what pxl8 discovered, and the tech apparently indicates there isn't a viable solution apart from all applications switching to using vector graphics.
It's not a solution, but it's a better technical understanding of what's happening.