Is the Islam of a discerning child who has not yet reached puberty valid?

There is a disagreement among jurists regarding the validity of a discerning child's conversion to Islam. The preponderant opinion is that their conversion is valid, because Islam is a purely devotional act that is validly performed by a discerning child, just as ritual purity (taharah), prayer (salat), fasting (sawm), and pilgrimage (hajj) are validly performed by them. The majority of scholars based their argument on the premise that Islam is a purely devotional act, thus it is validly performed by a discerning child, similar to prayer and pilgrimage. Al-Shafi'i and Zufar, however, cited the hadith: "The pen has been lifted from three: from the child until he reaches puberty," and argued that a child's conversion is a verbal declaration through which rulings are established, and therefore it is not valid for a child, as a child is not held accountable. Ibn Qudamah mentioned that the validity of a child's conversion to Islam is a matter of consensus, citing the conversion of Ali (may Allah be pleased with him) to Islam when he was a child.