In what respect did Gregory Nazianzen think the pure Nicene faith was adulterated at Constantinople in 381?

In contrast to the previous pro-Homoian emperor Valens, “it was soon clear that Theodosius would pursue a pro-Nicene line.” (LA, 251) In February 380 - only one year after he was declared Augustus and already a year before the ‘ecumenical’ council of Constantinople - Theodosius issued an edict saying: > “We (all citizens) shall believe in the single deity of the Father, the Son and the > Holy Spirit, under the concept of equal majesty and of the Holy > Trinity.” (LA, 251) As soon as “Theodosius had entered Constantinople in November 380," he exiled the Homoian bishop Demophilus and “accepted Gregory Nazianzen as de facto bishop.” (LA, 253) Gregory Nazianzen was one of the three Cappadocians. “It was … the first session of the council (of Constantinople in 381) that formally recognized him (Gregory as bishop of Constantinople).” (LA, 253) “Suddenly, Meletius (the presiding officer) died and Gregory Nazianzen became president of the council.” (LA, 254) However, “in the council itself Gregory seems to have quickly made himself unpopular.” (LA, 254) “At some point he seems also to have lost the support of Theodosius. Gregory offered his resignation … and it was accepted. In Gregory's place Nectarius, an unbaptized civil official in Constantinople, was chosen.” (LA, 255) Later, Gregory Nazianzen claimed “that at the council the pure Nicene faith was adulterated in the name of compromise.” In what respect did Nazianzen think “the pure Nicene faith was adulterated” in the creed formulated at that council? All references are to the book - Nicaea and its Legacy, An Approach to Fourth-Century Trinitarian Theology, 2004, by Lewis Ayres, Professor of Catholic and Historical Theology at Durham University in the United Kingdom.