Is the day's fast invalidated by the descent of three brownish drops five minutes before the Maghrib call to prayer, knowing that this was the beginning of the menstrual cycle? And are brownish discharges considered menstruation?

Brown discharge (kudrah) is considered menstruation if it occurs during the usual period or is continuous with menstrual blood without interruption. If these spots appear during the menstrual period, they are considered menstruation, invalidate the fast, and necessitate making up for it. It is also considered menstruation if it appears after menstruation and is continuous with it, provided that the total duration does not exceed fifteen days.