You are right that orthodox Christians of all sects reject the heresy of Nestorious. The point I believe is that the title of Theotokos or Mother of God, which is given to Mary was given to refute the Nestorian heresy not to claim she was the Mother of the God the Father, first person of the Holy Trinity.
And yet that's what is says.
Saying that she is the mother of Christ in no way denies either Jesus' humanity nor His divinity. It simply and accurately states a fact, which calling Mary the mother of God does not because it can be so easily misinterpreted.
I don’t know of any educated and thoughtful thoughtful Protestants who dispute Jesus was God from His conception...even though God the Son (with God the Father and God the Holy Spirit, One Being) subsisted from all eternity. In that sense, then of course Theotokos is an accurate description for Saint Mary, especially since it emphasizes the hypostatic union of two natures in one Person, Jesus.
This is not something orthodox Christians—of any stripe—dispute.
Nestorianism was...and still is, heretical.