What is meant by maḥīḍ in this āyah?

Imām Ibn al-Jawzī (d. 597/1201) summarized the scholars' opinions in his book "Zād al-Masīr" as follows:

1. It refers to menstruation itself. Those who supported this opinion argued that it is described as "a source of harm," which is characteristic of menstruation itself, not its location.
2. It refers to the place of menstruation, like "maqīl" which means the place of rest during the day, or "mabīt" which means the place of spending the night. [Qāḍī Abū Yaʿlā attributed this to Aḥmad] Supporters of this opinion point out that al-maḥīḍ could be a place noun which is then used for the phenomenon itself...They also argued that the harm could be due to impurity or an unpleasant smell, and some mentioned that intercourse with a menstruating woman could lead to a painful ailment.