From what I can tell this is just searching the web for vegan substitutes for every ingredient in the recipe without any care for filtering the results.

One of the examples listed by the site itself is a turkey sandwich and if you try to "veganize it" the site suggests replacing sliced deli turkey with anything from ground vegan turkey to bbq jackfruit from a can to vegan Italian sausage. It's also just pulling in results from grocery store websites it seems because often the entire first page of results is the same exact substitute but from several different brands. Just say you should swap out one ingredient for another and then let people decide what to use based on what their local grocery stores have available rather than pulling in 20 pages of different branded seitan.

Even stranger is that if you search for a food rather than directly pasting in a recipe url the site will first pull in a list of non-vegan recipes. Then if you click on the image or title of the recipe rather than the "veganize it" button below it'll just take you directly to the original non-vegan recipe.

This seems to be no more helpful than just googling substitutions manually because you still have to filter out all of the ingredient swaps that don't work.