Is prayer to be repeated when one performs an action within it, not knowing if it invalidates it, such as bowing for Rukūʿ while reciting the last verse of Al-Fatiḥah?

If someone doubts whether an action they performed in their prayer invalidates it or not, they should ask scholars. If it becomes clear that their action does not invalidate it, then that is fine. However, if it invalidates the prayer and they performed it out of ignorance, there is a difference of opinion among jurists regarding the obligation of making up the prayer. If someone completes reading Al-Fatihah while slightly bent in a way that does not remove them from the definition of standing, their prayer is valid. But if the bending is such that it is closer to bowing than to standing, then this is not valid, and the prayer must be repeated if they do not rectify it. The answer also draws attention to the fact that excessive questioning may be an indicator of waswasah (obsessive whispering/doubts).