others mentioned, but if this is pulled from bios of users, people use being vegan now as a sort of clout chasing/ideological superiority thing. Im not saying that every case of it being used is false, I just know plenty of people that have stuff like that in their bios for clout but dont follow it.

it would be infinitely more difficult to actually confirm who actually was vegetarian/vegan but would be a much more accurate graph rather than scrubbingbios (and if there is overlap or swapping between those groups based on people not knowing what separates the two)