Is taking a discarded medical bag from the street within the boundaries of the Haram and using it considered a sin? And what is required to be done about it?

If the treatment is simple and not commonly sought by ordinary people, then it is permissible to take and benefit from it. However, if the found object (luqatah) is not simple and was picked up from the Haram (sacred precinct), the majority of scholars believe that it is like a found object from outside the Haram; it should be announced for a period, and then becomes one's property.