What should a woman do if she starts menstruating on the seventh day of Ramadan after she has already performed ghusl and intended to fast, and is her fasting valid in this situation?

A Muslim woman should not hasten to perform ghusl (ritual purification bath) after menstruation until she is certain of its cessation, either by complete dryness or by seeing the white discharge (al-qassah al-bayḍāʾ). This is based on Aisha's statement to the women of the Companions: "Do not hasten until you see the white discharge." If she has purified and observed one of the two signs, and then blood appears, her fasting and prayers are valid, and the blood is considered dam fasad (blood of a disorder). However, if she hastens to perform ghusl before seeing one of the signs, then the blood is considered part of menstruation, and prayer and fasting are forbidden for her, and she must make up the fast of that day.