Maybe, but why would Jackie lie about that? On the meta level, why would they include that with no indication Star is wrong, like a note from Marco who is editing the book with her?
The fact that 2/3 of the "facts about Jackie" section were about her hair only draws further attention to it.>I'm pretty sure we've also seen her hair without it
Yes, in the preschool memory. The same shot shows her name as "Jakie" when it has since been established her name is "Jackie-Lynn."
Little things can change before they become important and there's several plausible explanations why the streak isn't in that shot.>What does this have to do with anything?
Providing a natural narrative lead-in to introduce Jackie as a non-human.
Similar to Star leaving the Diaz household opening the narrative possibility for her to end up in a relationship with Marco.
It's not hard evidence toward anything in particular, it just allows for more scenarios where a certain outcome is likely.