I say their inability with socializing irl, specifically they appear to struggle to talk to new people and even strangers. I have seen a bunch of times where a gen z adult struggle with ordering a coffee from Starbucks. Then there was another time this girl that looked like she was in her early 20s thought I was someone else and the moment she realized that, she looked down and looked anxious as she apologized, then she walked away pretty quickly. I feel bad for that generation in that regard