What is the deal with the gen z stare?

I’ve seen this happening for a while but never realized there was a term for it until now. I’m almost glad this is a universal experience and not just me? Lol.

For example- we take our kids to a gym daycare routinely, which has a lot of gen z caregivers. Truly every time I walk into the classroom, I say hi and get nothing but blank stares back. Our kids are happy there and they do good with them, but every time I say hello they look at me like I have two heads. No I do not have a personal relationship with these caregivers, but I see them weekly as I drop my kids off so they’re all familiar faces at the very least.

I’m a very introverted and reserved person, so I’m definitely not expecting their time and energy of a full conversation. But I thought a simple hello or acknowledgement of someone entering a room was just part of having good manners? It leaves me feeling so awkward each time it happens. Is this a new norm or am I just turning into a whiny millennial?