What is the ruling regarding blood that appeared at the time of the menstrual period, but differed in its usual color and quantity, and is prayer obligatory despite the presence of this blood or not?

The minimum period of purity (tahr) between two menstrual cycles is thirteen days. So, if a woman sees blood after this period, it is considered a new menstrual cycle. The minimum duration for menstruation, according to the majority of scholars, is one day and one night. However, according to the Maliki school, there is no minimum limit for its duration. If blood and its associated discharges of yellowish (sufrah) and brownish (kudrah) continue for a day and a night, it is considered menstruation; otherwise, it is not. The purity that occurs intermittently within a menstrual cycle is a valid purity, and the woman must make up the prayers she missed during the period of seeing this purity.