Is what came out after performing ghusl following menstruation considered menstrual blood, or is it purity, given that the bleeding had completely stopped before performing ghusl and the fasting was completed?

The fatwa (definition) we issue concerning the ruling on yellowish and brownish discharges is based on the Hanbali school of thought, which considers them menstruation if they occur during the customary period or if they are connected to blood. However, if they are not connected to blood and occur outside the customary period, they are not considered menstruation. Therefore, if you see brownish discharge during your customary period, it is considered menstruation, and you must make up that day's fast if you saw it before sunset. But if you see it after your customary period has ended, it is not considered menstruation, and your fast is valid.