As an early 90’s millennial, I’ve never noticed a “gen z stare” as described in news articles like a “blank face that shows lack of social skill or ability to think”. The only times I’ve witnessed it happen and seen the older person accuse them of “gen z stare” is when the older person says something off hand or dumb but isn’t self aware enough to realize they’re being weird. Hell, I’ve given people a blank face countless times because I was taught it was better to say nothing at all sometimes. Especially when it came to talking to older people at work.
I remember when I was 16, some middle aged guy at work accused me of having no personality. In reality, I kept all conversations short as possible with him (like almost everyone in the store) because they were casually racist and misogynistic.
I’ve always interpreted the stare as a consequence of growing up where cameras (phones) are everywhere and nothing ever disappears from the internet. And as a result people who grew up under that are ALWAYS cognizant of this. So they express nothing because it could make for embarrassing video or photos. Being extra or try-hard are also considered bad. Everything is tamped down, socially. They are seriously just repressed, internalized.
Yes, there is a feeling of the world is now a panopticon and anything you do or say will be used against you and taken out of context.