As an elder millenial I might have some insight. You know how when we were kids people used to get all up in their feelings when you weren’t smiling. That’s this. “Gen Z stare”, is just “Resting Bitch Face” or “You look prettier when you smile darlin’” repackaged and rebranded. They’re mad that the young people in general and women in particular aren’t running around with goofy forced smiles on their faces to make them feel special.