In his post-synodal apostolic exhortation Reconciliation and Penance, dated December 2, 1984, the Holy Father John Paul II spoke of current "wounds", whether individual or collective, and analyzed their causes.
"However disturbing these divisions may seem at first sight, it is only by a careful examination that one can detect their root: It is to be found in a wound in man's inmost self. In the light of faith we call it sin: beginning with original sin, which all of us bear from birth as an inheritance from our first parents, to the sin which each one of us commits when we abuse our own freedom.” (1)
However, a "knot" is not necessarily synonym with "sin": a "sin" implies responsibility and free consent, while the term "knot" is more general and can be assimilated to a trial allowed by God to make us grow in virtue.
In the episode of the blind man (Jn 9:1-12), Jesus answers a question from his disciples: "As Jesus passed by, he saw a man who was blind from birth. His disciples asked him, "Rabbi, who sinned, this man or his parents, that he was born blind?" Jesus answered, "It was not because he or his parents sinned; but so that the works of God might be made manifest in him."
So Jesus clears the responsibility for this man's illness: he is not blind from birth because he or his parents sinned. This example allows us to distinguish the difference between sin and knot, even though sometimes both coincide or one is the consequence of the other. Thus, to clarify the meaning of the word "knot," we can say that sin produces "knots," but that not all knots are the result of sin.
Isabelle Rolland. Marie qui défait les nœuds. D’un “miracle conjugal” à une dévotion universelle (Mary Undoer of Knots: From a "marital miracle" to a universal devotion). MDN 2022
(1) John Paul II’s post-synodal apostolic exhortation Reconciliation and Penance, introduction