“The Nestorian heresy is alive and well, I see.”
Whether or not that is true, I don’t think anyone here has taken a Nestorian stand. I certainly haven’t.
Christ is True God and True Man and Mary is His mother. She is not mother of His human essence only, because they are of one indivisible hypostasis. Trying to divide them (hypostases) commits the Nestorian heresy.