So while explaining the basics of world downloader I described the principle of chunks. As explained by the Minecraft wiki chunks are 16x16x256 section areas which make up your Minecraft map. Makes sense.
Yet when you make the chunk borders visible using F3-G (see attached picture) you'll suddenly find yourself in an 8x8 sized box. There are red "pillars" positioned even further away (as seen through the yellow raster) but even those are all aligned in an 8x8 sized gridset. Since the feature clearly specifies that it displays chunk boundaries I can't help but wonder if chunks really are 16x16 as documented or not 8x8 as hinted at with this feature.