Is it necessary to repeat the ghusl after seeing dryness and a yellowish discharge for a day and a night, then seeing dryness three times and performing ghusl, then a viscous thread-like discharge that is very light yellow, then a yellowish discharge for less than a day and a night?

The ruling adopted by us is that yellowish or brownish discharge is considered menstruation if it occurs during the usual period or is connected to blood. If the questioner sees it during her usual period, it is considered menstruation, and she must perform ghusl after it ceases. Otherwise, it is not considered menstruation.