It isn't. The truth is far more mundane: The actual "osu maple exclusive" content is likely a mislabeled, legitimate skin pack uploaded by a user named "MapleLeaf" on the official osu! forums in 2018. The "crack" part was added by clickbait YouTube channels to get views.
Subtly correcting the player's cursor pathing toward the center of hit circles, smoothing out shaky inputs. osu maple crack exclusive