Amoris laetitia in n. 83, says that the Church "firmly rejects the death penalty." The theologians censure a theoretically possible interpretation of this that would understand it "as meaning that the death penalty is always and everywhere unjust in itself and therefore cannot ever be rightly inflicted by the state." Such a meaning would contradict Church doctrine. Read in context, I don't see anything suggesting that the text would mean anything so absolute. As it is speaking about the Church's mission to defend life, the straightforward meaning of saying that the Church "firmly rejects the death penalty," would be that the Church holds with conviction that the death penalty should not be employed today.
Though it is not relevant to what the common Catholic would understood the text to mean, evidence for this reading is the way Pope Francis elsewhere describes Pope John Paul II's and the Catechism's position on capital punishment. E.g., in his address to the delegates of the international association of penal law, Pope Francis, referring to their statements that the cases where it is necessary to kill an offender are rare, if not practically nonexistent, says that "Pope John Paul II condemned the death penalty, as does the Catechism of the Catholic Church." So the weaker language of "firmly rejects" is adequately interpreted in this sense of being practically never necessary.
Pope Francis has repeatedly spoke out stronger against the death penalty. One may disagree with the prudence of this. But as there are not real indications that he intends to use the Apostolic Exhortation Amoris laetitia to further opposition to the death penalty or to change Church teaching on it, it would seem more well-advised to address those stronger statements, rather than raising concerns about what the statement "firmly rejects the death penalty" could be interpreted to mean.