I like the term "age indication". Thank you.

If I may nitpick, the conventional term for systems which attempt to determine the user's age is "age assurance". This covers a variety of techniques, which are typically broken down into:

* Age estimation, which is based on statistical models of some physical characteristic (e.g., facial age estimation).

* Age verification, which uses identity documents such as driver's licenses.

* Age inference, which tries to determine the user's age range from some identifier, e.g., by using your email address to see how old your account is.

These distinctions aren't perfect by any means, and it's not uncommon to see "age verification" used for all three of these together but more typically people are using "age assurance".