[IshKebab]

Yes it is dithering. Unusual dithering though - I don't see why it is coloured. Is this intended for printers?

[heftig]

The image gets de-saturated but the noise that's mixed in is colored. This looks like a mistake.

I think the noise is also way too 'soft'. At high frequencies it just becomes near-uniform gray so it barely affects the thresholding.

[kevinsync]

Yeah they could add grayscale to the filter rule to make the colors go away.

  #dither-demo img.dithered {
    filter: url(#dither) grayscale(1);
  }