I’m still in my 20s, but as of a few years ago I started forgetting what’s my exact age. I always have to stop and recalculate it each time someone asks me. I get asked fairly infrequently, but when I do it’s a bit weird/embarrassing that I have to say “wait, let me calculate”. (I know when I was born, of course.)
It seems as if there’s no good reason I’d remember it, since it changes all the time and it is rarely mentioned in practice. But others, including people much older than myself, know their own age immediately.
I’m also terrible at remembering people’s names, I don’t know if that could be related?
You’re not alone, I started not really remembering around that time too… Birthdays just weren’t a big deal anymore and there was so little call to bring it up once I was old enough to legally buy alcohol.
Eventually, you get to the point where you’d like to forget, and you may ask yourself, how did I get here?