Twitter has changed how it awards blue checkmarks. It used to be that the blue checkmark meant Twitter had just verified that someone of note was on the service and that this was their legit account. Over time, however, Twitter took the position that in handing out blue checkmarks it was somehow finding the person's comments acceptable.
As a result, white supremacists have seen their blue checkmarks gone. Some people have, with pride, tweeted things to get Twitter to revoke their blue checkmarks. And Twitter has willingly obliged. It did not want to give verification to white supremacists and anti-Semites.
But Louis Farrakhan is a noted anti-Semite. He is no fan of white people or Jews and his racist rhetoric is as awful as many of the white supremacists whose blue checkmarks Twitter has revoked. So why does Twitter treat Farrakhan differently from the other racists and anti-Semites? Are they willing to endorse his conspiracies against Jews, etc.?