Technically it is a "back rank mate" however the use of the dark bishop to support the rook makes it feel like an "opera mate"
You mated on the back rank, so yeah its a back rank mate. Not sure about the Opera Mate thing. Gotta check.
Technically it is a "Piece-helped back rank mate"
Not back rank mate. It is mate
Not every checkmate delivered on the back rank is a back_rank_mate.
@Sarg0n Every rule has an exception.