We know the Patripassions were abusing it to say Jesus was the Father in the second century. We know that Hippolytus who refuted them nevertheless indicates it does refer to Jesus as God, only that he is not the Father.
If not God the Father, then what God was Christ?
At that time I am not sure if anyone even spoke of “God the Son”. (Modern ECW translations have to be approached with caution, they can flip Son of God to God the Son.
Hippolytus seems to have a real problem with Romans 9:5.