

A quick search led me to this one:
https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/does-vaping-cause-popcorn-lung
The tl;dr edition though: no one has ever gotten popcorn lung from vaping. Yes, diacetyl is dangerous to inhale, which is why it was removed from legal flavorings a solid decade or so ago. Cigarettes contain more diacetyl than vape flavors did though, and no one has ever gotten popcorn lung from smoking cigarettes either. It’s a common story that gets repeated with circular citations and won’t go away.
No, that’s a filly buster.