Versus populum practice is ancient enough on it’s own, there is no teaching that is contradicted. Same way Orthodox Church changed liturgies to better reflect faith- nothing wrong with that either. Roman Catholic Church shares pre-schism Fathers with Orthodox Church- except Roman Catholic Church holds to Ecumenical Councils. Ecumenical Council proclaimed to be in agreement with Augustine and follow him in “all things”. However, Orthodox nowadays reject Augustine despite their own Ecumenical Council supporting him. There is simply too much contradiction in Orthodoxy.
Orthodoxy has primus who is Ecumenical Patriarch of Constantinople- who was made Ecumenical because of practical reasons, despite Alexandria and Antioch (and even Jerusalem) having much better claim for it based on tradition. Nowadays though, there is no practical reason for Ecumenical Patriarchto be in Constantinople (Istanbul), yet Orthodoxy keeps him as primus. Why is that, if tradition did not matter back then and practical reasons did, that today it is reversed just to suit Constantinople?
Russian Orthodox Church not only rebaptizes people, which is contrary to Orthodox teaching and was solved in dispute with St. Cyprian, but also used to forbid many other things such as unleavened bread’s use for Eucharist (Patriarch Michael Cerularius did not want to deny allegations of stepping on it), but nowadays it is alright for Western Rite to use. Mortal and venial sin are criticized as Latin concepts, yet many Orthodox theologians write about them and Western Rite acknowledges them. Schism of 2018 in Orthodoxy does not help either, as it shows there were 2 uncanonical actions of Patriarchs yet Pan-Orthodox Council can’t be called because of lack of authority. Nevermind that, Orthodox Patriarch still excommunicate each other for jurisdiction issues over each other.
Orthodox Church has beautiful heritage from Eastern pre-schism Catholic Church to which it holds dearly and follows many wise and good teachings, possesses true sacraments and valid priesthood, and unity impairment with Catholic Church is very small and we can one day hope for reunion, but Orthodoxy clearly has issues that just show it is not real Bride of Christ.