Is light brown discharge or brown blood appearing on the sixth day after purification considered a new instance of ghusl that necessitates abandoning prayer and fasting?

If what a woman sees on the sixth day is merely a yellowish or brownish discharge (kudra) and not normal blood, then it is not considered menses. She should perform ghusl after seeing dryness on the fifth day, then clean herself (istinja') and perform ablution (wudu') for prayer when she sees the kudra. However, if the blood is red and recognizable, then it is considered menses as long as it occurs within a period in which menstruation is possible.