What is the ruling on prayers performed with the letter alif in "ihdina" pronounced as a ya, due to ignorance?

If the alif in "ihdina" (guide us) is replaced by a pure ya' while one is capable of pronouncing it correctly, the prayer becomes invalid. However, if the ya' is not pure and resembles an alif with a slight phonetic error, the prayer does not become invalid, because it is a hidden mistake (lahn khafi). Regarding making up past prayers if they were invalid, the view of the majority of scholars is that making them up is obligatory. However, Shaykh al-Islam Ibn Taymiyyah holds that making them up is not necessary due to the hardship involved, and he argued that the Prophet (peace be upon him) did not order the one who prayed incorrectly to make up what had passed. Nevertheless, making them up is more cautious to avoid the disagreement of the majority.