A friend of mine has a CBD processing lab and CBD distillate crashed to about $1,000/L in 2019-2020, and hasn’t recovered afaik but I haven’t asked him in a while.
Synthetic cannabinoid products exist, but they’re not commonly sold as anything but synthetic cannabinoids.
This was not scaremongering, I bought some myself. Twice.
I have connections with people in the old synthetic cannabinoid industry and know how cheap that shit is to buy and how easy it is to order from China, so I don't see in any way it being a stretch of the imagination to envisage people growing poor quality weed and adding to it.
I don't know about the US, but in Germany its common practice to spray either legal CBD weed or regular weed with synthetic cannabinoids and sell it as "Haze". The same goes for hash.
This practice has been widely publicized and is regularly confirmed through tests (see drug checking websites). A quick Google search will demonstrate the abundant availability of the raw materials (fake hash, legal CBD weed, synthetic cannabinoids, fake packaging). Besides this objective evidence, it is both my personal experience and common knowledge on Germany's streets that laced weed is the norm at this point.
Its obvious that this would happen when there is no regulation but strong financial incentives to produce this crap. Many customers don't care or explicitly look for the much stronger high that these laced products provide.
All it takes is one state: Berlin, Bremen, Hamburg — come on people!
----- Edit: Bremen has a famous digital debt clock showing how much money the state owes. Perhaps there should be a similar clock showing how much money the state loses due to the illegality of cannabis (combination of criminal justice costs and expected tax receipts). That might spur the conservative rationalists.