What is the ruling on repeated confusion in prayer between Dhuhr and Asr, when each obligatory prayer is performed on time in congregation?

The specific intention for a prayer is a condition for its validity. So, if the worshipper does not intend the specific prayer or intends a different one, their prayer is not valid, because specifying the prayer distinguishes it from others. If, after praying, the worshipper becomes certain that they intended a prayer other than the one they performed, then their prayer is invalid and they must repeat it. However, if it is merely a doubt after finishing the prayer, this doubt does not affect the validity of the prayer.