It used to be the case that no lethal drugs were potent enough to be active in the tiny dosages that LSD was distributed in... so you could feel pretty safe in taking it.

Unfortunately, that has not been the case, as there are now very potent and potentially lethal drugs like Bromo-DragonFLY[1] that are active in similar dosages to LSD.

So you really need to test what you get.

[1] - https://psychonautwiki.org/wiki/Bromo-DragonFLY