What is the ruling on one who memorizes the Holy Qur’an without the rules of recitation (Ahkam Al-Tilawah), while excelling in reading and avoiding grammatical errors?

A Muslim must learn the rules and fundamentals of Tajwid for reading and memorizing the Qur’an. Whoever neglects it while being capable of learning it is sinful if that leads to obvious errors (Lahn Jali). As for subtle errors (Lahn Khafi), they do not reach the level of prohibition.