Forum Thread
Font change
Forum-Index → Bug Reports → Font change
Zoomed in Screenshot of the Pokeradar instructions as an example. Blue is the old font from december, Red is the current font as an overlay to compare. Both screenshots have been aligned with the big line under 'instructions' to show the difference.
Also, on the Forum page the thread names look like they are bold now.
So, as loketoke suggested, it might be from an update of my PC. I checked on my old laptop (that uses Windows 8) and the font still looks like its supposed to be.
Edit: more things we checked are Windows Font size (still set to 100% like before) and Firefox Zoom (also at normal 100% as it is supposed to)