I have a date I use that's incorrect, but consistent so I can remember it if I need to, that I use for age verification for anything that doesn't truly need an accurate birthdate (example, age verification to view games on Steam).

It's roughly the same age as mine, but if someone tried to pass themselves off as me with that birthdate, they wouldn't succeed.

These companies are mostly just verifying I'm an adult anyway, and I am legit that.

But yeah, I don't like just giving the actual date everywhere as it can potentially be used for identity theft.