What about Faustina Kowalska? A nun and “mystic” reported of having apparitions with Our Lord. However, things said by Him were not in accordance with the teaching of the Church. Why do I recall, in her reports, that Christ said confession was not necessary?? I could be mistaken, but there was something similar to that. John Paul II canonized this nun and even he was canonized later. Some say these canonizations are invalid.
I have even heard that praying the Divine Mercy chaplet (which has come from the reports of Faustina) is actually demonic. Were her reports condemned by the Church? Correct me if I’m wrong.
Her work was condemned by the Holy Office twice, once under Pope Pius XII and again under Antipope John XXIII. I've read the journal myself, and there's a lot of weird things in there that are unbecoming of a genuine mystic. In particular, there's the weird incident where the Host jumps out of the Tabernacle and places Itself in her hands, almost implying that Communion in the hand is acceptable.
The one that really stood out to me, though, was early on in the journal the circuмstances surrounding her entrance into the Convent. Her parents expressly forbade her from entering, yet she disobeyed them (still being under their charge) and entered anyway. This is in contradistinction to the Saint that Sr. Faustina (and the Divine Mercy "devotion") tends to mirror: St. Margaret Mary Alacoque. St. Margaret Mary not only obeyed the whims of her ill mother on refusing her entry into a Convent, but also obeyed the will of her brother once she was put under his charge. It was only when she was given the go-ahead by her brother that she was permitted to enter the Convent. We all know God loves obedience to lawful superiors, so for Sr. Faustina to open her religious life on the grounds of disobedience is a big red flag for me.
Another such issue are the very weird appeals to pride made by the "apparitions" of Our Lord to Sr. Faustina. Namely, how "He" stated to her: "I am uniting myself with you so intimately as with no other creature.” An extremely odd thing to say, given that the Incarnation through the Blessed Virgin is the most intimate union possible between God and Man. Not only that, but Sr. Faustina was lamenting that her Convent did not have its own saint, with "Our Lord" replying: "Don’t cry. You are that saint." If you're at all familiar with Saints and their visions of Our Lord, He doesn't say things like this to them. At all. He typically will reiterate to them their own nothingness in order to crush any lingering pride in their souls and foster humility. He did this repeatedly to St. Margaret Mary Alacoque.
Lastly, the mere fact that this "Devotion" promises what basically amounts to a second baptism on "Divine Mercy Sunday" is scandalous. And the emphasis it lays on the Mercy of God has opened a door within the Novus Ordo to the all-encompassing ecuмenism and religious indifferentism through these appeals to God's Mercy. It has all but eclipsed the Sacred Heart devotion with its practice and promises within the Novus Ordo. And, in my opinion, appears to be wholly demonic and instrumental of the new false religion.
https://www.traditioninaction.org/HotTopics/f072_DivMercy.htmhttps://schismatic-home-aloner.com/sr-faustina-divine-mercy-chaplet/https://cmri.org/articles-on-the-traditional-catholic-faith/the-divine-mercy-devotion-why-did-the-holy-office-ban-it/