Is a very slight yellowish discharge (ṣufra) after the days of bleeding and brownish discharge (kudra) considered a state of purity (ṭuhr) that necessitates prayer, especially if the discharge period exceeds 15 days? And is supplicating for the reduction of menstrual days considered an transgression in supplication?

A woman's supplication for the regularity of her menstrual cycle and the reduction of its days is not considered an transgression in supplication. If the days of bleeding, yellowish discharge, and brownish discharge exceed fifteen days, then the woman is considered to be in a state of istihadah (definition) (prolonged vaginal bleeding outside of menstruation), and she must consult the fatwas related to the rulings of istihadah.