As late as the 11th century, only seven councils were recognised as ecumenical in the Roman Catholic Church. Then, in the time of Pope Gregory VII quoted the prohibition in canon 22 of the Council of Constantinople of 869–870 against laymen influencing the appointment of prelates elevated this council to the rank of ecumenical council. Only in the 16th century was recognition as ecumenical granted by Catholic scholars to the Councils of the Lateran, of Lyon and those that followed.
This explains why the Eastern Orthodox only accept seven Councils. I always wondered why it wasn’t eight with the Fourth Council of Constantinople in the ninth century? I didn’t realize the Church could accept Councils it rejected centuries later. It actually kind of is questionable to me unfortunately; as if the Church can just use a document to justify itself and then accept a previously rejected Council in spite of it.
Does this mean the Church could technically stop accepting a Council as well?