There never was a popcorn lung outbreak in vapes. Lipid pneumonia is not popcorn lung. Freebase nicotine is water soluable so it’s always been dissolved with glycol. THC is fat soluable so it was what was causing the lipid pneumonia. Popcorn lung is a very specific disease caused by diacetyl and I’m unaware of any cases of that in vapes, none the less an outbreak. There was never going to be a lipid pneumonia with nicotine though, because nicotine does not dissolve in oil and we use vegetable glycol as a thickener because of that.

Popcorn lung was largely a concern for DIY vapes in the early days that used food additives haphazardly to create flavors. The dangers of diacetyl were recognized quite early though and folks made sure they weren’t using it.