One of the commenters of your post says "If we legalize it we can better research it". Allow me to be rude -- this is BS. If we follow this logic we should legalize pretty much everything!
I think it is polite to be rude to such dangerous thoughts. Downvote me as you see fit.
Governments should not be in the business of banning things unless there's a clear and present danger. Citizens should have the autonomy to do risky things if they want to.
Acetaminophen is the one that still mysterious, there are credible theories but they don't explain everything the substance does. The latest one I know of is that one : https://www.pnas.org/doi/10.1073/pnas.2413811122