The history of Jansenism Part IV
Unigenitus Dei Filius is said to have marked the official end of toleration of Jansenism in the Church in France, though quasi-Jansenists would occasionally stir in the following decades. Jansenism persisted in France for many years but split “into antagonistic factions” in the late 1720s. By the mid-18th century, Jansenism proper had ceased to be a viable current within Catholicism.
However, certain ideas tinged with Jansenism remained influential much longer; in particular, the Jansenist idea that Holy Communion should be received very infrequently, and that reception required a lot more than freedom from mortal sin, remained influential until finally “condemned”/rejected by Pope Saint Pius X, who endorsed frequent communion, as long as the communicant was free of mortal sin, in the early 20th century.