What about the hundred thousand Japanese American internees in American concentration camps? I don't think the scale is that different, normalized by population and stage of development.
We should be critical of human rights violations of every country, at every point in time. Past US violations are not some kind of excuse to allow China to put millions of people in concentration camps. This is a fallacious argument, the tu quoque logical fallacy.
As a non-black person, it'd be like me criticizing black people for things they do. Since I cannot truly understand the black experience in America without being a black person, any criticism I levy against them would be wholly unfair.