Mixing stimulants and opiods, colloquially called a "speedball" is more dangerous than using either alone. What happens is that the stimulant counteracts the high, (and the breathing suppression), so the user takes more of the opiod than they usually would, and then when the stimulant wears off, they have much more of the opiod than they can tolerate, and they die from an overdose (the rebound of the breathing suppression). Traditionally it would have been cocaine, which wears off much faster than meth, meaning that this would happen when both were administered at the exact same time, (or in the same injection mixed together), ...but that doesn't mean that Floyd didn't take meth hours before, then took a shit ton more fentanyl than usual to "chill out", and then the meth wore off before the fentanyl did, and then that overdose of the fentanyl killed him.

Mixing stimulants and opiods, colloquially called a "speedball" is more dangerous than using either alone. What happens is that the stimulant counteracts the high, (and the breathing suppression), so the user takes more of the opiod than they usually would, and then when the stimulant wears off, they have much more of the opiod than they can tolerate, and they die from an overdose (the rebound of the breathing suppression). Traditionally it would have been cocaine, which wears off much faster than meth, meaning that this would happen when both were administered at the exact same time, (or in the same injection mixed together), ...but that doesn't mean that Floyd didn't take meth hours before, then took a shit ton more fentanyl than usual to "chill out", and then the meth wore off before the fentanyl did, and so then then an overdose of the fentanyl killed him.