Does the prayer of one who says, "Subhana Rabbiya Al-Azim" instead of "Subhana Rabbi Al-Azim" become invalid?

It is permissible to vocalize the "ya" in "Rabbi" (My Lord) with a fatḥah or to keep it quiescent during the tasbih (glorification) of bowing and prostration. The matter is broad, and there is no harm in either case.