Odd issue. I noticed it yesterday when working with a sync and backup folders. Never noticed that before cause I've never pay attention in detail. Dunno if it's right or wrong. Weird for me. See? Fonts, or sizes, are different between dialog box... Just the window title fonts are equal, I guess.
it may be something with display auto DPI scaling? I have had same sort of odd effects on Win 10. As long as i can read it i just ignore the fonts