Firebase Analytics demographics

Question

The Firebase Analytics dashboard shows a card for demographics, including age and gender.

According to https://support.google.com/firebase/answer/6317486?hl=en Fireb

Answer 1

On Android, this data is derived from the Advertising Id, which is automatically collected on devices with Google Play Services installed. On iOS, this data is derived from the Advertising Identifier (IDFA) when available (i.e. when your app links to the Ad Support Framework). AdMob is not a prerequisite for Age, Gender or Interests on either platform.

Clarifying note from comments: Firebase Analytics demographic reports is thresholded for privacy reasons. Once you have enough data -- at least 10 users per age/gender bracket -- data for that bracket will be shown.