It’s a ticking time-bomb. Flavour ingredients are allowed to be used to give aroma (which is 95% of taste) to foods. These molecules are ingested and dealt with by the stomach or passed straight though but the flavour molecule diacetyl, which gives the butter flavour to popcorn, has already been found to cause lung damage in eight workers in a popcorn factory (Google Popcorn Lung).
That would have been eight people who didn’t deliberately inhale the molecule in a water vapour, which I imagine would increase absorption into lung tissue. So we have no idea what long-term damage is being caused by inhalation of flavour molecules.