The entire structure of the monarchy is inherently racist - I wrote about it a long time ago. The idea of supporting a black woman into the monarchy is flawed at inception, the whole thing needs to be abolished. This is why I'm so baffled by the lack of woke take up for the full abolition of the monarchy which seems like the only logical opinion. However, there's an entire tranche of the British public that will argue for equality and fairness then go and wave flags for people who have a magical bloodline.

https://medium.com/p/f6d91949c638

As for the treatment of Meghan Markle, it has nothing to do with racism and everything to do with the supercilious, contradictory, batshit and codependent nature of Harry and Meghan. They simultaneously don't want to be part of the royal family but want all the perks. They want to live in obscurity but launch Netflix specials and give interviews. They want their cake and to eat it too. They want to save the world and take private jets everywhere. They're the epitome of hypocritical idealism and they're treated as such - they have enough money to live a comfortable middle class life in obscurity - and we have the precident of Edward VIII as a blueprint. That's not what they want.

So yes, the answer is racism... but not the way you've shaped it. Monarchy is the epitome of systemic racism, the treatment of Meghan Markle is a result of her actions with very little to do with her skin colour.