I saw that and thought it was a neat, elegant way of doing that type of dragon. It makes sense: they have a history in the Realms so nothing is really being added there.
The original post is now deleted. It gave a clue to a dragon not of the standard ten "colors". As I stated above, I don't think it is the first such beast in official 5E material.
The variation compared to previous editions is still minimal, though.