Just because something is bizarrely rare doesn’t mean it doesn’t happen. I’ve never heard of such. I mix my own juice though. I’m wondering about additives or bizarre reactions to common chemicals. Vape juice is a blend of several things and weird stuff might be added to the particular juice you are using or a particular rare reaction to a particular flavoring or other chemical. I might consider a totally different juice. If it was a fruit try something that isn’t a fruit at all. Say, a custard maybe. If it was a salt try unprotonated. (Or the reverse) different maker. Different atty. get away from it and then add things back in till it happens again. Then you will know what is causing it. It’s wildly rare though. I’ve been vaping for over 10 years (2008) and I haven’t heard of it happening. My guess is it’s a particular flavoring mixed with a particular genetic profile, but I’m just throwing stuff at the wall.