Are the light brown discharges that precede menstruation considered menstruation that prevents prayer, and is the blood that follows the purification from the original menstruation considered istihada (abnormal bleeding) that necessitates prayer?

A brownish discharge (Kudra) at the time of menstruation is considered menses if its duration reaches one day and one night. As for blood observed a week after the cessation of menstruation, it is considered menses if its total duration, combined with the period before it and any intervening purity, does not exceed fifteen days; otherwise, it is irregular bleeding (Istihadah (definition)).