It's a very recent development in the language; one of the ripples that radiated out from the George Floyd protests.
The NY Times hosted a piece that explains the reasoning behind it: https://www.nytimes.com/2020/07/05/insider/capitalized-black...
The NY Times hosted a piece that explains the reasoning behind it: https://www.nytimes.com/2020/07/05/insider/capitalized-black...
Minor quibble, but political opinion, not "language".