Is the prohibition against suppressing the two urges (urination and defecation) during prayer for the purpose of complete prohibition (haram) or mere disapproval (makrooh), and what would be the diverting factor if it were for disapproval?

There is no prayer in the presence of food, nor when one is suppressing the two excretions (urine and feces). The prohibition of this is so that the heart may be free for worship. This indicates that the prayer is valid if completed, but it is disliked if the suppression is light and does not disrupt the prayer, and forbidden if it leads to disrupting the obligatory acts or pillars.