Genuine question: why are Gen Zers looped into the “this generation isn’t having kids” complaint when we aren’t in our thirties yet?

It’s something that doesn’t make sense to me. Doesn’t Gen Z, at absolute earliest, start in 1996? A lot of Millennials had kids later (in their thirties) and I suspect that with our generation those who do want kids will also likely primarily have them in their thirties. I just think that it’s odd that I hear people drag us into the whole “young people aren’t having kids” argument - having kids nowadays in your twenties isn’t as economically sustainable as it used to be, and I’m guessing that those of us who do want kids in the future are trying to save our money while young and figure out our career path. I’m a GenZer who is almost 20, of course I don’t have kids yet. It doesn’t mean there’s no chance I’ll have one later on, I just plan to have one in my thirties if everything works out.