S ephora stores are being overrun with tweens pumping product testers. Eight-year-olds film themselves on “Sephora hauls” and GRMW (get ready with me) videos , applying collagen boosting serums and retinol creams for their nonexistent wrinkles. And party bags are stuffed with face masks and fluffy headbands, instead of glitter and gummy bears. The rise of Sephora kids is a widely reported issue, but the uptick of children “obsessed” with skincare has some experts concerned about the long-term effects of age-inappropriate products and increased occupation with appearance at such a pivotal age. A new term has entered the lexicon: “cosmeticorexia”, meaning a preoccupation or fixation with “flawless” skin. Last month when Italian authorities cracked down on big beauty brands for allegedly targeting younger and younger shoppers, they cited cosmeticorexia as a cause for concern.…