What is the ruling on the fasting of a woman who took pills to prevent menstruation in Ramadan, and light-colored blood came out of her during the period of taking the pills, so she broke her fast, thinking it was menstruation?

If blood appears at a time suitable for menstruation, for instance, if the previous menstrual period was followed by fifteen days of purity, and this blood continues for a day and a night, then it is menstrual blood. The meaning of its continuation is that the area remains stained, such that if a cotton swab or similar is inserted, it comes out colored with it, and this condition persists for a day and a night or longer.