Prayer in a direction other than the qiblah relying on phone applications

The questioner:
Honorable Shaykh, may Allah grant you success, a student in the university housing has been praying the obligatory prayers in his room for the past four years, making them up (qada'), in a direction other than the qiblah, relying on an application for determining the qiblah. It has now become clear to him that the qiblah he was praying toward was not correct. His question is: what is obligatory for him?

The Shaykh:
We must know the extent of his deviation from the qiblah. If it is significant, such that the qiblah is to his side or behind his back, then his prayer is not valid. However, if the deviation does not reach the point of placing the qiblah behind him or to his side, his prayer is valid. The Prophet (peace and blessings be upon him) said: and the East is the qiblah. This was in Madinah, meaning the qiblah is broad, praise be to Allah. One who does not see the Ka'bah prays in its direction. It is not a condition for that to hit the exact spot of the Ka'bah, but rather to hit its direction, as long as he has not deviated from it, his prayer is valid.

The questioner:
Honorable Shaykh, may Allah grant you success, this questioner says:

The Shaykh:
Also, the one in a country should ask the people and look at the mosques and their mihrabs. Yes.