I’ll be honest, I don’t buy this. I don’t see why fan artists should be expected to draw their depictions of pre-Nightmare Moon Luna based on a minor detail that only appeared briefly in the intro of the first episode of the show. If this was the only glimpse into their appearances at the time… than yes, perhaps. But we have seen actual flashbacks of Luna and Celestia in their younger days in the show – actual looks into that period rather than illustrations in a book written who knows how many centuries after the fact – and if anything, they are evidence against Luna and Celestia having had solid-colored manes of any sort during the times of Discord and Nightmare Moon.
 

 
In the flashback of Celestia fighting Nightmare Moon in the Season 4 premiere, she already had her aurora-like mane. Since this book here depicts her with a solid pink mane, it’s already a blow against its accuracy in that regard. If it got Celestia’s mane wrong, it’s entirely possible it got Luna’s wrong, too.
 

 
And indeed it did, because in the next flashback in that episode we see that even in Discord’s time – thus necessarily before the events in the book – they already had their modern-day ethereal manes and tails, conspicuously lacking in any sort of swirls.
 
The only visual evidence we have of what they would have looked like with solid manes are Luna’s brief appearance in her “depowered” form,
 

 
And in the Legends of Magic comics,
 

 
And in neither case are swirls of any kind present (although interestingly enough, Celestia appears to have had green and blue in her mane from the get-go).

@J4m35  
Don’t speak for everyone.

@Pokefound  
You mean OP?  
Because he made more then on post on this and even acted like people can’t see the non-existent problem.

@Pokefound  
i am completely baffled how you came to that conclusion  
like seriously, what  
you have to read that in a pretty extreme tone to turn it into being triggered

Pssst, hey buddy! Yeah, you!  
I gotta tell you something!
 
 
_{No one cares.}

@Prof.NightJack  
triggered much?

Dude, stop, it’s an instillation from a book, not a real image of a young Luna.

the thing there is, young luna’s art wasn’t based on these images, it was based on, y’know, the actual young luna seen in the show, so