How can we advise worshipers who recite the Quran in a colloquial dialect that changes letters, such as (ذلك) to "zalk" and (مبثوث) to "mabsous", considering their constant argument that it is their dialect and they cannot change it?

Reciting [the Quran] in a colloquial dialect is not permissible if it results in changing a letter from the Book of Allah. Those who do so must be advised and warned about the seriousness of their action. The argument of inability to change one's dialect is a weak one, for learning is possible. Whoever experiences difficulty will be rewarded. They should be advised with wisdom and gentleness, and the Imam of the mosque should be informed to give them a lesson. Likewise, the rules of Tajweed (definition) should be learned and applied.