my favorite part of these flat earth maps is how latitude and longitude apparently have no real meaning and are treated as just lines on a piece of paper.
Are you suggesting there are large blue lines painted across the ocean? Or are they just lines on a piece of paper?
Are they real or are they man-made is essentially the question.
I think the answer is: "a bit of both".
But, yes, lines of latitude do represent something tangible which relates to reality, so they can't just be added willy nilly to a flat earth map.