It might be okay to identify a group of people by their year of birth but then attributing a quality or similarity to every member of THAT group is ageist. You are then verging on using the term in a pejorative sense.
Why are you doing that? Because you want to feel better about yourself…? I hope not.
If this were the only example, I’d not say anything. But I’m sad to report that many people use such terms dismissively as if they applied to whole swathes of people. It is ageist. Stop with it! PLEASE!