Do some scholars consider dark discharge menstruation but not yellowish discharge, and what is their evidence for that?

Yellowish discharge: a yellow fluid resembling wound exudate. Brownish discharge: a fluid mixed with redness.

Brownish and yellowish discharges are the same in ruling. If they appear outside the days of menstruation, they are not considered menses. However, if they appear during the days of menstruation, they are considered menses.

Scholars have not differentiated between brownish and yellowish discharges, except for what was narrated from Abu Yusuf al-Hanafi in a specific case: their appearance during the menstrual period before the blood itself. If yellowish discharge appeared before the blood, he considered it menses. However, if brownish discharge appeared before the blood, he did not consider it menses. But this opinion is rejected because both are types of blood, so whether they appear first or last, they are like other blood colors.