How is "wa la al-dalleen" recited in prayer, and does reciting it as "wa la ad-dalleen" invalidate it?

It is obligatory to read "walad-dallin" with the letter ض (dad). Whoever intentionally replaces the letter ض with another letter, their prayer is invalidated. However, if the replacement is due to an inability to learn, then their prayer is valid for themselves, and it is permissible for them to lead in prayer those who are in a similar situation. The prayer of one who is able to correct the letters of Al-Fatiha becomes invalid if they pray behind such a person.