The detailed descriptions on DDG and Google are both exactly the same size, 13px. I think the people complaining about these visual issues are imagining things.
Font size isn't exactly comparable across different font families. In the case of DDG they are using DDG_ProximaNova, while in the case of Google they are using Arial.
Arial is much easier to read on Chrome for Windows over DDG_ProximaNova.
I also just noticed that we can change the font on the settings page, just feel like it shouldn't be necessary.