I think the blacks are more referring to the "soft R" version, "nigga" which for whatever reason they thought was a cool word for them to adopt and call each other. So they don't think Whites should use either one of them which is bullshit. As I recall the shift started around the time reddit banned r/waterniggas, after that the rules got strict. I call my friends my nigga cause it's funny and have been for years with no complaints. I even call them nigger sometimes if they're acting like one. In my mind anyone can be a nigger.