Do you remember the times when you knew nothing and cried behind the imam because you were so moved by his recitation and the moment of prayer in congregation?
Do you then remember the more recent times when you had learned your tajwid and instead of shedding tears in the prayer were focusing on the errors of the Imām?
It is not uncommon at all that a student who has just finished some of his tajwid studies starts to pay more attention to the mistakes and slips of others in the prayer. This is natural, but it is not healthy if it goes so far that you actually forget what you’re doing, i.e. praying to God All-Mighty.
If the nafs is not curbed, your great knowledge might not only make you have bad manners with others but might even make you lose the khushu’ you had in your prayer as an ignorant layman.
Think about that for a moment.