What is the ruling on purity (ṭahāra) if bleeding stops and yellowish-beige discharge appears, then the blood and discharge cease for an hour, and the tissue comes out clean except for dirt-like specks that disappear upon touching, then a pink drop appears hours later?

The sign of a woman's purity from menstruation is dryness. The criterion for this is that she inserts a piece of cloth, and it comes out clean, with no trace of blood, yellowish discharge, or brownish discharge on it. Any dampness she finds does not matter, because the vagina is usually not free from moisture. The sign could also be the white discharge (al-qassah al-bayda'), which is a white fluid that follows menstruation. So, whatever dryness a woman observes is considered a valid sign of purity, and any secretions that follow are not considered menstruation if they occur outside the usual period of her cycle.