If so, has the Moscow Patriarchate (MP) renounced it?
Was the current head of the MP, Patriach Kirill a soviet agent?
On January 19, 1918, he anathematized the bolsheviks and their co-workers, saying: "I adjure all of you who are faithful children of the orthodox church of christ not to commune with such outcasts of the human race in any matter whatsoever". Addressing the pastors and archpastors, he said: "Do not hesitate for a moment in your spiritual activity, but with fiery zeal call your children to defend the rights of the orthodox church which are now being trampled on. immediately organize spiritual unions, call on them to enter, not of necessity but voluntary, into the ranks of the spiritual warriors, who oppose external force with the force of their holy inspiration..." The decree ended with an appeal to defend the church, if necessary, to the death.
That should be the governing document for the condemnation of Sergianism. The Russian Orthodox Church Outside Russia (ROCOR) condemned Sergianism as heresy, albeit after it broke apart following talks with MP; the Moscow Patrirachy never did. This an article that makes reference to anathema by Russian Orthodox Autonomous Church (ROAC) and the most recent anathema by ROCOR remnant (Agafangel):
To those who label the Godless power of Antichrist, ’blessed’, and not merely permitted by God; to those who dare work for these secular authorities for the purpose of a false-appearance of the outward Church arrangement of the Holy Church; to those who for the sake of pleasing worldly power trample God’s commandments, the holy canons, the Patristic tradition and the catholicity of the Church; to those who deny faith or honor to the holy martyrs and the confessors of Christ, who hurl blasphemy at them and who deliver them into the hands of their torturers; to those who justify Yudin* thinking and action and who speak of themselves as if possessing some sort of ‘special’ wisdom and salvation outside the Church; to those who respect and obey the temptation of the antichrist, prepared as though given to him by God; to the Sergianists, the new Renovators, ANATHEMA! And let all cry out three times, ANATHEMA! ANATHEMA! ANATHEMA!
Patriarch Kirill certainly has KGB ties, and at the same time we are not likely to ever know their extent:
In the early 1990s and later on, Kirill was accused of having links to the KGB during much of the Soviet period, as were many members of the Russian Orthodox Church hierarchy, and of pursuing the state's interests before those of the Church.[32][33][34][35][36][37] His alleged KGB agent's codename was "Mikhailov".[38]