I usually like to figure things like this out a bit more before I make a post about it, but I still don't really have any idea how this works. As far as I know this is the only place in the game where you can do this, I haven't had it happen anywhere else thus far at least.

If anyone has any idea about what is going on here, then I'd love to find out. It's a bit precise, but it's not that hard. I don't really have a setup or anything, I just do the strat I usually do, but mash the jump button at the end.

The video below shows me getting the triple jump two times at normal speed and then once at 20% speed.