A quick Google search puts the birth year range for Gen Z between 1997 and 2012, so between ages 9 and 24. That's like peak teenage years. You have some younger than that, some older than that, but the majority are going to be right in the middle. Plus, as much as 20 year olds like to pretend that that aren't cringey teenagers anymore, that behavior doesn't just change on your 20th birthday, it's a process that happens over time. I'd say I still had cringey teenager tendencies until I was at least 22 or 23.

I'd say what the person above you said is perfectly accurate. Gen Zs are pretty much in peak teenage years right now.

Edit: so I think the article Google gave me was 2 years old. Still, it would put Gen Zs between ages 11 and 26. I think the point still mostly stands.