What is the ruling on reciting Surat Al-Fatihah by repeating the verse "You alone we worship and You alone we ask for help" seventy times before completing the Surah, and is this considered an alteration of the Qur’an?

This action was not transmitted from the Prophet (peace be upon him) nor from his Companions. Had it been good, they would have preceded us to it. Therefore, drawing closer to Allah by reciting Al-Fatiha in this manner is considered an innovative addition (bid'ah idafiyyah) that is rejected, and it is impermissible to do it or draw closer to Allah Almighty through it. This action is not disbelief (kufr) nor an alteration of the Qur'an, but it is among the reprehensible innovations. So, you must follow the Sunnah and shun innovations.