Not true, AT ALL. There is NOTHING about black Panther that requires him to be black. His power is not linked to his skin melanin content. He ought to be AFRICAN, but that is a place to be born, not an ethnicity. I can think of a hundred ways for a non Sub-Saharan African person to be in Wakanda. Hell, Wakanda could have been where Cleopatra fled to with Marc Antony, faked their deaths, and the WHOLE COUNTRY is HELLENIC GREEK/EGYPTIAN. See how that works????For example, let's take a look at black panther. Born in a hidden city near central africa, he is part of a thousands of year old nation of black people on wakanda that were isolated and unknown to the the of the world for thousands of years. There were never any colonization or slave trading going on. He eventually ascended to the throne he was born into. His entire story in the black panther film is about how his nations isolationism prevented them from doing something about the evils of racism against black people for thousands of years and the ramifications of that.
He HAS to be black. The white black panther narrative misunderstand this completely. His story requires him to be black. You cannot tell that story if he's white, and it would not make any sense for him to be white because that nation was never colonized.
I'm fine with Wakanda being all black as a mythology aimed at African Americans. But then I'd also argue that Middle-earth is a mythology aimed at Northern Europeans and well, we see how that goes.