Samin is not beating the cigarette mom allegations
In Ep. 54, Ryujin mentions that continuously using essence can actually give you a growth spurt. White (Min) and Samin were supposed to look older than their actual ages, because they've been abusing their essence for a long time (Kid Sayeon's friend's dad mentions that teenage Samin has been passing herself off as an adult, and White is pretty tall for an Asian dude).
Sayeon was supposed to undergo a similar transformation-- becoming leaner, taller, and meaner-looking-- after joining the Aberrant Corps. It would have been like a second puberty. This is, of course... not obvious in the slightest... because HJumper's art changed so drastically between Season 1 and 2 that any differences in Sayeon's appearance can now be chalked up to a difference in style. Whoops!