In the chili-head community, these stomach aches are well known as "cap cramps" (capsaicin cramps) and it happens to just about everyone while building a tolerance to capsaicin. Over time and continued eating of mega hot stuff, these cap cramps get less severe and the amount of capsaicin ingested in order to trigger cap cramps increases as tolerance builds.

Competitive pepper eaters actually make themselves vomit after eating large amounts of super hots in order to avoid the cap cramps, they can last for double-digit hours to if enough is consumed.

These cap cramps send a lot of folks to the hospital if they don't know any better, but they haven't been life threatening for healthy adults. The data just isn't there for that.

A lot of people will also over indulge on dairy thinking they are helping the burn in their mouth, but drink a half gallon of milk in one sitting and it upsets stomachs, too.

I'd be interested in knowing how the study at the University of Mississippi directly correlated the stroke to the hot pepper a full two days after ingesting, that seems like a stretch to me. What is it about the mechanism of capsaicin on receptors that would cause a stroke?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7136587/

This is the study. There was no stroke for this person, but what they call reversible cerebrovascular vasoconstriction syndrome. He presented two days after the pepper, after football practice, for a headache that wouldn't go away.

The study never says the pepper caused the issue, but it is hypothesized.

Further, if you dig into the links in the study of other examples of extreme reactions to hot peppers, you have

A) esophageal rupturing after a bout of violent retching a vomiting after eating a ghost pepper

B) acute myocardial infarction and coronary vasospasm by someone taking cayenne pepper pills for weight loss where the abstract is just postulating capsaicin was the cause, but end of the day dude was taking diet pills

C) some nothing burger abstract about someone having a thunderclap headache after eating a super hot

There isn't even an adequate sample size to be statistically significant with regards to capsaicin being the root cause for any of these issues, not to mention none of these studies are actually confirming their abstract to any reasonable degree.

I'm not saying the chip didn't lead to this young man losing his life, but there is no worthwhile scientific data pointing to that being a legitimate reason. This is an outlier case I'm interested in the outcome and I feel for the young man's family, but my hypothesis is that we'll find out any correlation to the one chip challenge will only be tangentially related.

So how are they achieving that, what ingredient is not listed?

Ingredients I see (at least on the search result from the official website, likely cached) say blue corn and blue 1.

The page itself with talk of the 2023 version doesn't list anything about blue (and explicitly says in the FAQ that there's no dye), so maybe they gave up on that.

If I recall, the chip I ate was a virulent green. I expect blue die made a yellow chip green.