Whitewashing in this context doesn't makes sense to me, it not something that you should be referred to as in general, and if are mixed or light skinned that was not your choice, it's not something you should be abused with especially in the wrong context its being used.
Also anything that doesnt align with the majority of black culture tends to be seen as white, especially in terms of how you act or how you talk.
(it's something I was always aware of, black people questioning why I talk white, white people asking why I don't talk black (ghetto) .. I'm not even white but sure keep up the stupidity you know lol)
But it does remind of the case of Australian history, the program in which the idea that aborigines could be breed out to become whiter, intentionally trying to 'white washing' a culture to extinction.
But whitewashing more commonly prevelant when it comes to media, films and TV mainly especially that of a proven historical nature, where non white culture is represented by some who is white in appearance and has no connection to said culture because it was deemed more profitable or palatable for the main audience, thus has always been a prevalent issue in America.
Black Community itself suffers alot from the drawbacks of severe assimilation, in which in order to be seen as anything, beautiful and worthy 'white was right' even though not all the world believes that notion nowadays (Although is still quite prevalent across countries still) the effects of being seen as less especially as a dark skinned person has taken its toll over the years, where we have people bleaching their skin, and the ever so divided 'war' of light skin vs dark skin black people.
Not much has changed since I was a kid, even in the UK those with light skin was seen as more desirable than those with dark skin. (I'm mixed but I was not the right kind of mixed, dark skinned mother and Filipino Chinese father, I was seen as a mutt, unlike the half white/black kids)
However its not great on either side of that coin regardless.
On a non related note white washing is a technique used for wood and such orginally nothing to racial issues.
But its also used in a similar tense in which someone glosses over an issues or something that has real importance, somewhat downplaying the stituation.
I got lost somewhere... I wrote too much but I hope its understandable.