In the West, we’ve forgotten that Pope Liberius was celebrated as a saint for over a millennium, with his feast day on 23 September. Venerable Cardinal Caesar Baronius‘ 1586 revisions of the Roman Martyrology removed his feast, possibly to avoid further conflict with the Protestants. Pope St Liberius refused to condemn St Athanasius, for which he was briefly imprisoned. While imprisoned, he was forced to sign an apparently semi-Arian document, an act he repented of later.
In the East, he is still celebrated as a saint, with his feast on 27 August.
In the 1960 Divine Office, he is mentioned in the readings of August 5, and is said to have been visited by Mary, the Mother of God, in a dream.
When Liberius was Pope, a Roman patrician named John, and his wife, also of noble birth, having no children to inherit their goods, vowed their inheritance to the most holy Virgin Mother of God. The Blessed Virgin heard their prayers and approved their vow by a miracle. On the 5th of August, which is that time when the heat of summer waxeth greatest in the City, a part of the Esquiline Hill was covered by night with snow. And on that same night, the Mother of God told John and his wife separately in dreams that they should build a church on that place. When John told this to Pope Liberius, he said that he had had the same dream. The Pope therefore went to the snow-covered hill and there marked out a site. The church was built with the money given by John and his wife, and was later restored by Sixtus III. It hath been given various names; but, so that its title may indicate its excellence, it is called the Church of St. Mary Major.
— 1960 Divine Office, 5 August, Matins, Reading 3
Pope St Liberius, pray for unity between
the Christian East and the Christian West
Holy Pope Liberius – there is a place for reparation … Transalpine Redemptorists
The Alleged Fall of Pope Liberius … Transalpine Redemptorists
Saint Liberius, Pope of Rome … Orthodox Church of America
List of Popes of Rome … Orthodox Wiki
Divinum Officium, Rubrics 1960