Okay found this tweet from Fiona Hering (Fashion Features Director VOGUE NL/ ambassador Orange Babies)
In English:
I think that's partly true, cause it's obvious they want brunnetes. BUT also blondes are still doing high profile shows (not talking about Anja, Natasha) and other brunettes like Laura K, Josefien, Arizona, Jac etc are also not getting booked. Also a designer fave with blonde hair normally stil books the show..
I think a combination with her blonde hair AND the thing above we can;t discuss. i bet if the thing above wasn't a part of this problem, she would have booked at least Versace.