What is the ruling on prayer and fasting during the days when blood and brown discharge appear before the usual menstruation due to contraceptives, with the bleeding stopping for a day and then menstrual blood appearing? And is this considered menstruation?

If a woman sees blood and associated brownish discharge during a time suitable for menstruation—after thirteen days or more from seeing purity, and the total days of bleeding and what follows it of normal blood and purity do not exceed fifteen days—then it is menstruation, obligating her to refrain from prayer and fasting and to perform ghusl upon its cessation. The intermittent purity within this period is considered valid purity. However, if the total of the two bleeding periods and purity exceeds fifteen days, it is istiḥāḍa (non-menstrual bleeding), and only what coincides with her previous habit is considered menstruation.