This page shows a few examples of Firebase ID tokens:

GitHub

{
  "name": "Thai Pangsakulyanont",
  "picture": "https://avatars.githubusercontent.com/u/193136?v=4",
  "iss": "https://securetoken.google.com/firebase-project-id",
  "aud": "firebase-project-id",
  "auth_time": 1657452028,
  "user_id": "firebaseUid",
  "sub": "firebaseUid",
  "iat": 1657463997,
  "exp": 1657467597,
  "email": "______@______.__",
  "email_verified": false,
  "firebase": {
    "identities": {
      "github.com": ["193136"],
      "email": ["______@______.__"]
    },
    "sign_in_provider": "github.com"
  }
}