issue in Passport v12.3 unsupported_grant_type

Question

I'm using Passport v12.3 in a Laravel project. I encounter an issue whenever I try to check the access_token for any user; I get this error. I've tried many things, but nothing worked. I saw a solution for the problem which suggested that Passport::routes() needs to be added in AuthServiceProvider, but Passport removed this method after v8. So, what could be the reason?!

{
  "grant_type": "password",
  "client_id": "client_id_here",
  "client_secret": "client_secret_here",
  "username": "user@example.com",
  "password": "user_password",
  "provider": "users",
  "scope": "*"
}

{
    "error": "unsupported_grant_type",
    "error_description": "The authorization grant type is not supported by the authorization server.",
    "hint": "Check that all required parameters have been provided",
    "message": "The authorization grant type is not supported by the authorization server."
}