Originally Posted by
RedBird
It was a thing in canon for a very short time, but it became a bigger thing in fandom, so much so that DC now sprinkles it in every now and then.
Technically it showed up first in Batman: Hush, and had only appeared in other main continuity comics like once or twice and that was about it. After the new52 it wouldn't really appear again until around rebirth, and even then, it would only be in non canon books/titles/animations.
But despite the fact that it was a small detail that had not been in continuity for long, the fandom kind of latched onto that visual feature for years, especially in fan art, so now many fans have come to associate it with the character. Since Rebirth and Infinite Frontier, we've seen the white streak make a comeback, appearing more and more frequently in non canon books and comics covers, but as far as I'm aware, it still hasn't actually made an appearance in the main continuity. (Unless that Robins mini series is considered in continuity since that book did in fact feature Jason with a white streak)