Question

Hello Rabbi,
Following an argument about whether or not one may eat fish with milk, I wanted to know: in prohibitions like these, which are forbidden for a reason that seemingly is not halakhic / of Jewish law (because of danger), do the Sages have substantive authority?
In other words, even if I am not convinced that they are right, since doctors today do not think there is any danger in this at all, am I still obligated to listen to them by virtue of their authority?

On the one hand, authority even in such prohibitions is possible (and perhaps the fact that the Talmud prohibited meat and fish proves that such authority exists),
but on the other hand, seemingly this is not a halakhic / of Jewish law question at all (except perhaps for “and live by them,” but I would violate that prohibition only if the doctors are mistaken, which is unlikely), but purely a medical question.

Thank you