What is the ruling on clothes that were washed with garments stained with menstrual blood, and the stain was not removed until later? And what is incumbent upon one who wore some of these clothes, prayed in them, and they became wet, causing the defilement of carpets or other clothes?

The person afflicted with waswasa (obsessive doubts/whispers) should disregard these intrusive thoughts and refrain from dwelling on them. For washing menstrual blood, it suffices to use water to remove the visible trace of blood. There is no need to use soap or other detergents. The persistence of the blood's color or its trace after washing does not cause harm. So, if the garment is washed from menstrual blood and its trace remains, this does not impair the completeness of purification or the validity of prayer, due to the ease and leniency present in Islamic law.