The previewed pages in the browser also have incorrectly sized fonts.
If I reduce the resolution of the monitor to 1920 x 1080, all fonts are rendered correctly. Everything also renders correctly when edited on my laptop (1920 x 1080).
The software version is 14.3.2
Windows 10 64bit.
GTX 1660 graphics card with up-to-date drivers.
Also notice that in the 4K image the fonts show a lot more aliasing than the lower resolution, which is the opposite of what would be expected.
1920 x 1080
3840 x 2160