I reject the entire premise altogether - Hollywood is not whitewashing anything, and I find the terminology of "people of color" vs. "white" itself disingenuous and racist. White is also a color....
The majority of Americans and Brits (Hollywood has been casting plenty of Brits lately) happen to be Caucasian/White, therefore the majority of roles in Hollywood/American films are going to go to white people.
No one talks about "Brownwashing" in Bollywood (Indian) cinema when a brown person of Indian heritage plays a part in a Bollywood movie that was historically a white person, and to suggest such an accusation would be ridiculed as laughable. The only reason it happens in America is because of the history of segregation, slavery, and white nationalism/supremacy and the resulting "white guilt" Western phenomenon of the 21st century that perpetually victimizes and infantilizes all non-Caucasians completely ignorant of context.
Sure, some roles where whites have played other ethnicities have rightfully been construed as exaggeratedly stereotypical or racist (Mickey Rooney's infamous role for example), but that's entirely different than just happening to cast someone white in a role whilst not making a mockery of another race. Plus, there have been roles where whites were portrayed by actors of other races in similarly degrading ways, but no one cared.
In fact, when you crunch the numbers, non-white minorities are OVER-REPRESENTED in Hollywood films when compared to the general population of Americans, or even Californians... but no one seems to recognize that, despite it being rather obvious. There have been plenty of non-white actors cast as characters who were historically white (Will Smith as Dr. Robert Neville in "I Am Legend", for example) and yet these casting decisions are nothing but celebrated - and I don't for a second think there's anything wrong with it either, the role is about whether an actor can convincingly portray someone, not what the color of their fucking skin is.
Progressive liberal society purports to want to end racism and stop racial injustices, but in many cases I believe they are the ones perpetuating it.