User blog comment:Harbumz/Introducing Vignette, Wikia's New Thumbnailer/@comment-11842624-20150212224531/@comment-31845054-20150212225003

This specific image (I assume you're talking about http://vignette3.wikia.nocookie.net/arezista/images/3/30/Na_flag.svg/revision/latest/scale-to-width/300?cb=20141227071733&path-prefix=ru) was created before one of the more recent SVG fixes was pushed out. Eventually, these images will "fix themselves" as they expire from various levels of caching, but I've gone ahead and manually replaced that image, and it looks much better :D