Since I last used atom I installed Wine and I understand as part of the process of intalling Wine some new fonts are installed. For some reason the font in the editor of Atom has changed to a very ‘ugly’ one, I’m not sure why it changed at all.
font-family rule that apply on text editors was referencing a font that wasn’t available at first it use a fallback. Then if the wine installation added this font then it’ll start using it, which would explain the sudden change of render after the wine install.
You can verify which font apply with the chromium inspector in the devtools.