Dope was originally heroin (or in the really old days, morphine), but over the last few years it has increasingly come to mean "a mix of opioids and other drugs

Dope was originally heroin (or in the really old days, morphine), but over the last few years it has increasingly come to mean "a mix of opioids and other drugs/adulterants". As the article references, it's a lot more likely to be fentantyl, which is stronger and cheaper than heroin. Given the relative potency I would imagine that its proportionally a lower percentage of fentanyl compared to heroin, but I don't recall the article specifying.