https://www.youtube.com/watch?v=1XI_kTHgO7M
lol
basically if you play lucio you know youre only allowed to slide on the same surface once. most surfaces have a bunch of junk on them that count as new surfaces, so you can ride around usually for a long time, but will eventually clip the edge of something and end up falling. numbani basically throws that once per surface rule out entirely and theres not many obstacles in the way, leading to stuff like this being possible.
i hope they dont change it. none of the other maps are quite like it and it makes the hero funny to play