IMO nothing happened. It's made me irritated to see all these comments of, "what's going on, bodybuilders are dropping like flies." In reality only a few died, most likely no more than average. If they wanted to dig deeper they could've added to the list for sure. "What's going on, this IG page is like an obituary page, I'm going to stop following you, something needs to be done about all these deaths." No, you're not going to stop following, tragedy tickles the senses, it's exciting as unfortunate as that is - it's tragedy porn and it sells.
If a hot batch of gear ripped through the bodybuilding industry, stuff that killed people, like for example extra potent fentanyl laced heroin does in the dope world, then we could be talking of "what it's related to."