"AT THE COLUMBIA JOURNALISM REVIEW, we capitalize Black, and not white, when referring to racial groups. Black is an ethnic designation; white merely describes the skin color of people who can, usually without much difficulty, trace their ethnic origins back to a handful of European countries."

As you've noticed, this became:

"AT THE COLUMBIA JOURNALISM REVIEW, we capitalize Black, and not white, when referring to groups in racial, ethnic, or cultural terms. For many people, Black reflects a shared sense of identity and community. White carries a different set of meanings; capitalizing the word in this context risks following the lead of white supremacists."

I think this would be controversial. While a lot of White Americans are proud of their ethnic background (I'm a quarter Irish!, I'm an Italian American), many are not. Maybe because they have mixed backgrounds, don't know where their ancestors came from, or because their ancestors fought or fled wars with those European ancestors. For instance my great-grandfather left Europe in disgust after WWI, and after coming to America told his family that they were going to be simply Americans.

According to wikipedia, 6.6% of Americans self-identify their ancestral origin as simply "American". Most of these are visibly white. Many of them are descended from British people, and quite possibly don't want to self-describe as British-American because America was founded by a war to terminate that connection. https://en.wikipedia.org/wiki/American_ancestry

The change is to refer to "the Black identity" instead of race. Whatever that means.