I like your screen name, and I was raised Lutheran, lol. Calvinism always seemed a little foreign to me but people who consider them staunch Calvinists should know that the “eternal subordination of the Son” is something Calvin would not have supported, nor Luther, and not for that matter the Catholic or Orthodox churches, for for that matter, traditional Baptists. This seems like something that was borrowed a bit from Arianism.
Thanks. You are correct, this eternal subordination of the Son is not orthodox and Calvin himself, who did hold to the Apostles and Nicene Creed, would reject it. It is a form of Arianism and is also correlated with other Christological problems, Nestorianism and the Monophysites, which holds to the notion that Christ is 1 Divine Person (rejects Nestorianism) and He is has both a Fully Divine and human nature (which rejects the Monophysites).
It is indeed problematic on many fronts. Good to see on this front, Traditional Catholics, Orthodox and Historic Reformed groups (Calvinist and Lutheran) can still agree on these historic Doctrines related to the Trinity and who Christ is.