What is the ruling on the Salah of Qasr (shortening prayers) for someone who is hesitant between staying and traveling?

A traveler must perform the full prayer if they intend to reside in a country for more than four days; this is the view of the majority of jurists. However, if they are uncertain about the duration or their stay is for a need whose end is unknown, then they may shorten the prayer.

The opinion that a resident may shorten the prayer unless they intend permanent settlement is held by some scholars, and there is no blame on one who follows it. However, the more cautious and safer approach, which is the view of the majority of scholars, is that if a traveler intends to reside for more than four days, they must perform the full prayer. This is to prevent laxity and to exit from scholarly disagreement.

Therefore, the prayers you shortened in Madinah while residing there for months must be re-performed, unless you sought a fatwa from someone who permitted shortening or followed someone who holds that view.