Answered by: Maulana Shadman Ahmed
An Imam makes a serious mistake in his Qiraat. The mistake is of nature which breaks the Salaah:
أ. What is the condition of his Salaah if no one corrects him from behind?
ب. What is the state of his Salaah if someone does correct him?
In the name of Allah, the Most Gracious, the Most Merciful
Regardless of if someone corrects him from behind or doesn’t correct him from behind if an imam makes a serious mistake where the meaning of the ayat changes then the prayer will be invalid (Fatawa Mahmudiyyah, vol. 7, pg. 118-121).
Only Allah knows best
Written by Maulana Shadman Ahmed
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham