What is the ruling on blood that appears during the usual time of menstruation, but is light red or pink and has no odor; is it menstruation or istihadah (non-menstrual bleeding), and what are the consequences if a woman does not perform ghusl from it, believing it to be istihadah?

The default is that all blood a woman sees is menstrual blood, regardless of its color or smell. Distinguishing between types of blood and their signs is resorted to if the bleeding continues for more than fifteen days. If the total number of days of bleeding does not exceed fifteen days, then all of it is menstruation. If ritual purification (ghusl) was neglected after the cessation of bleeding due to ignorance, there is a difference of opinion among scholars regarding the obligation to make up the prayers that were performed.