What is the ruling when a follower (Ma'mum) invalidates their prayer but the Imam's prayer remains valid?

Primary text

If a follower commits an act invalidating prayer, such as being in a state of minor ritual impurity (muhdith), having impurity on their person (najasah), or committing an act like laughing, speaking, or omitting a pillar (rukn), and this is only discovered after completing the prayer, or if the invalidation occurs during the prayer, the ruling follows the Imam's prayer, provided the follower is the only one praying behind the Imam. The ruling is that the follower's prayer is judged the same as the Imam's prayer because the connection between the Imam's prayer and the follower's prayer is reciprocal. Whatever invalidates one invalidates the other in this context, and whatever is valid for one is valid for the other.