iTunes did another one of its seemingly random minor updates again the other day. And today I opened it to watch one of the few podcasts that I use still use it for only to notice that it looked a bit weird.
As it turns out Apple has finally (and this is a real finally) adopted HiDPI support on Windows. From their release notes,
This update is designed for high DPI displays so text and images appear sharper and clearer. It also includes minor app and performance improvements.
I would guess that they got a little push in this direction since iTunes is supposed to be moving to the Windows Store, but it is 2017, and HiDPI has been a thing for over five years. There are complaints about it not scaling correctly above 250%, but this fixes one of the last major desktop apps. Not a minor thing when many laptops come with 4k screens now.