This is set in a fantasy scene that is also based the Arthurian history, yes historically it's "not correct" but this isn't based entirely on medieval times and the author is allowed to take creative liberty. I also believe the author didn't just think "nah everything will be fine" it's called being inclusive.
"nah, everything will be fine" i meant reaction of other fictional characters on it.Like Morgana with black skin...
If that happens story even can't begin.
About creative liberty, many people somehow forget that works in both ways.If is allowed to add black people in Medieval society, especially in higher classes , so must be allowed to make a film which places somewhere in central Africa during Antiquity or Medieval Age and pictures tribe where people have white skin*.
But in similar cases when black people pictured as white many as you unhappy with that and exist special term for that.Which is kinda really strange - if you okay with this why you not okay with similar?
*Personally hate this too.And unlike many people i will hate both things, without being hypocrite and telling that one thing awesome but similar - bad.
My opinion on creative liberty in fantasy - If anyone want to make fantasy with all kind of these things just make your fantasy world or choose one where they look believable and not messing with existing original descriptions.