The study I posted in my initial comment notes how easy it is to reach near lethal levels for a healthy adult (second article, as well as myself, notes that most folks aren't healthy) with the current trend of supplements, powders, and additives in other foods. Other studies have noted that high/toxic levels of caffeine can and does lead to varying types of death, including suicide, but also major cardiovascular issues.
We don't take it seriously enough, but we've always done this. Used to put cocaine in cola too. Regulations just haven't caught up with it yet.
It's possible your space isn't federated with those communities yet? You might need to start the link with searching for them using the !instance@web.site command to force your instance to download their pages first.