Does the prayer of one who intended that facing the Qibla is a pillar and remembered during the prayer that it is a condition become invalid?

It is clear that the questioner suffers from whisperings (waswas), and he should ignore these whisperings and not succumb to them. The validity of prayer does not depend on knowing all its detailed rulings theoretically; what is important is to perform it correctly. So, if a person prays in its correct form, his prayer is valid, whether he knows the difference between a fard (obligatory act) and a sunnah (definition) (recommended act) or not, or if he believes all of them are obligatory. The proof for this is the saying of the Prophet, peace and blessings be upon him: "Pray as you have seen me praying." Therefore, the man who believed that facing the Qiblah was a pillar (rukn) and then remembered it was a condition (shart (definition)), his prayer is valid, and he must beware of succumbing to whisperings.