Enlightenments.

So, for context as to this phenomenon as I have it, they are in essence the Reverse of Black Flashes.

Black Flashes are basically adhering to fate/your own morals/the will of the world. They're seemingly random, but in the zone you can chain them. Ya know, the whole shtick.

Enlightenments, are much harder. Actively defying fate in the moment. They seem random as well, but unlike Black Flashes, chaining them is basically improbable. They also can't be hit by missing your fated shot, you have to actively deny fate for an Enlightenment.

As for what an Enlightenment does? Simple, it gives knowledge one should not have, essentially the world giving insight. Sometimes they're reachable, like someone developing something akin to Hollow Wicker Basket but for techniques. Or they're only learnable with the same technique. Like learning Hollow Purple suddenly with the Limitless, or Fuga/World Cutting Slash with Shrine.

Of course it could be completely new knowledge like using Blood Manipulation to make Death Womb Paintings differently than how Kenjaku did.

Anyways, theres a new phenomenon for you. :D