What is the ruling on stopping memorizing the Noble Qur’an at the mosque near our home because of the sheikh who makes mistakes in memorizing the Noble Qur’an, does not correct the students, and jokes with the verses of the Qur’an?

There is no harm in ceasing to memorize with a shaykh who is not proficient in recitation. Memorizing the Quran is not an individual obligation (fardh 'ayn), but it holds immense merit. Therefore, be keen to memorize with a shaykh who is proficient, even if it requires effort to go to him. It is advisable to return to the first shaykh to benefit from his knowledge, and to gently guide the shaykh who is not proficient to the necessity of ensuring the accuracy of what he recites to people.