Does what a breastfeeding woman saw in terms of discharge, between yellow and red, for one day, count as menstruation, and what are the consequences of that?

It appears that what the woman sees as a brownish discharge is considered menses if it continues for a day and a night; otherwise, it is not considered menses by the majority of scholars. In the latter case, it only necessitates istinja’ (cleansing the private parts) and nullifies ablution (wudu’).