I remember there were stories of hospitalized young adults with pneumonia who hadn't use weed carts, only were using legit tobacco vapes. Could be they just didn't admit to using illegal carts of course.

Edit: here's a research article, there was a small CDC study early in 2019 where all the patients had vitamin E in their lungs, but a larger study later in 2019 only had 86% of patients reporting cannabis use, and another in 2020 where they only found vitamin e in 49% of patient samples.