Is it by the colour of their skin that you judge? Even on that basis you’d have a problem. Colour of skin means nothing. A black woman and a monoracial black man will make a black child. A black person and a person of another race will make a mixed race/biracial child. Genetics. That's what I'm going with. A mixed race person can be any colour and a black person can be any colour. Doesnt change what they are.
You must appreciate that not everyone agrees with your philosophy on this of course, haven't said everyone does or else I wouldn't be posting if everyone did.
This idea that black people are being replaced by mixed race people who are called black or who identify as black is ludicrous and dangerous thinking in my book. By replaced, I don't mean people in life. I mean representation-wise in the media. If you can't see it, you've either chosen not to or you have mixed-race privilege which allows you not to see it. I'm not sure you've read the links I gave.
Fwiw, part of my own family is mixed race. My husband is biracial and I have a lot of mixed race family members from my husband's side. My husband opened my eyes further to this even though I always thought of this. He's has these sort of discussion in the media.
Are they not black enough for you? There's no such thing as black enough or white enough. If you're black, you're black. If you're white, you're white. If you're mixed, you're mixed. Theres no "enough" because there's no one way of being any if them behaviour wise/skin colour wise.
If you don't see it, you don't want to see it because it somehow benefits you. It's time we all came out and told the truth about our different privileges.