https://apastyle.apa.org/style-grammar-guidelines/bias-free-...

I know it's a recent trend but I thought the capitalization was applied to all ethnicities.

To quote the link you posted:

>"Racial and ethnic groups are designated by proper nouns and are capitalized. Therefore, use “Black” and “White” instead of “black” and “white” (do not use colors to refer to other human groups; doing so is considered pejorative)."

However, the NYT:

https://www.nytimes.com/2020/07/05/insider/capitalized-black...

>"The Times also looked at whether to capitalize white and brown in reference to race, but both will remain lowercase. Brown has generally been used to describe a wide range of cultures, Mr. Baquet and Mr. Corbett said in their memo to staff. As a result, its meaning can be unclear to readers; white doesn’t represent a shared culture and history in the way Black does, and also has long been capitalized by hate groups."

Edit. Side note. Maybe I should write to the NYT and tell them I'm a White African and they're not representing my cultural and historical identity!