Is the brownish discharge that came from the wife, then temporarily stopped before intercourse, and returned thereafter, considered menstruation that necessitates expiation upon both spouses?

Slight discoloration is not considered menstruation unless it occurs during the customary period or is connected to blood. If the wife experiences purity and informs her husband, there is no sin upon them for engaging in intercourse. And whoever has intercourse during menstruation, being ignorant of the ruling or of the existence of menstruation, is not obligated to do anything.