Many illegally sold drugs are now lightly dusted with fentanyl. I have no interest in opiates but always test any substance I use to ensure I’m not getting an opiate additive. Cannabis dusted with fentanyl is more addictive and produces a stronger high, which is why the cartels etc do that kind of thing. Same with other drugs - adding tiny amounts of fentanyl leads to more repeat sales for black market sellers.

The argument around legalize, test and regulate would help ensure the safety of recreational drugs in general, and reduce the black market’s ability to lure people to more addictive and thus profitable substances.