Low quality, high risk
Fentanyl can be made cheaply from chemicals. It’s mixed with other drugs to make them stronger. Fentanyl is found in cocaine, methamphetamines, molly/MDMA, and counterfeit pills that look like real medication.
Even if you know and trust the person who gave you the drug, it still could contain fentanyl. Learn the signs of an overdose, and be prepared to act.