So it's just a 4K screen with resolution set to 1080p and scaling set to 100%? or what?
I saw the similar issue in OS X but I've never observed it in Windows o_O
The problem is in the default OS font size. UI elements that have extremely large fonts on your picture are set to the "default font size", while others (that look "normal" on the picture) set to some explicit values like "9 pt" or "11 pt".
The bottom line is it's not a scaling issue but some system fonts are configured in a very unusual way.