"auth_time" claim in the tokens is always zero for Direct Grant

Issue

When I tried to use the auth_time claim in the access token or ID token to show the login time, I found it is always zero for Direct Grant (Resource Owner Password Grant).

{
  "exp": 1669711332,
  "iat": 1669711032,
  "auth_time": 0,
  "jti": "be484cb1-a918-4343-8a30-eafb4975bcf0",
  "iss": "https://auth.example.com/auth/realms/demo",
  "aud": "demo-client",
  "sub": "0c7c9d63-d938-4561-b5a1-9d102896bfbb",
  "typ": "ID",
  "azp": "demo-client",
  "session_state": "1e7c611d-4b8b-4ffb-a00d-511ee9a4c535",
  "acr": "1",
  "sid": "1e7c611d-4b8b-4ffb-a00d-511ee9a4c535",
  "email_verified": false,
  "preferred_username": "john@example.com"
}

How can I retrieve the login time from the RH-SSO server?