I have an issue similar to this one.
The solution however did not work for me.
In the editor and when running the game with normal window size (unscaled) the fonts look crisp and sharp. (I have filtering and anti-aliasing turned off for the fonts)
When I use the test size however the fonts get extra semi-visible pixel around them (lerping??), probably caused by the scaling...
Does anybody know how to get the fonts rendered pixel perfect?
Edit: This only occurs on my fonts with size 32 pixels. For all my other fonts, sizes range from 8 to 26 pixels, they get rendered perfectly.
Window Size: 384 x 216
Test Size: 1536 x 864