Of all terrible proposals coming up in this period, I'm still more-or-less ok with this system because the administrator is still in full control to set whatever date they want, and the field is entirely optional.

They call it "age verification" in the aricle, but there's no 3rd party "verification" whatsoever. It's just a field for the user birth date saved in the user metadata. This is IMHO acceptable because it doesn't force anybody to provide IDs or personal information to some random shady company.

I think calling it "age verification" is a bit confusing and will make people unhappy by default, but might be a smart move to make it compliant with the new laws coming out in this period (the user age was "verified" by the system administrator, after all).