Firebase Auth: Why using identitytoolkit signInWithCustomToken after some time the refresh token request response PERMISSION_DENIED?

I have an implementation on my react site to authenticate with a custom token returned by my server, for this, I use firebase.auth().signInWithCustomToken(token) I understand what if you use this kind of authentication this provides an automatic request (https://securetoken.googleapis.com/v1/token?key=[myApiToken]) to refresh the token after the expiration time of this. but when this expired my application began to fail the request with the following response:

   {
  "error": {
    "code": 403,
    "message": "Requests to this API securetoken.googleapis.com method google.identity.securetoken.v1.SecureToken.GrantToken are blocked.",
    "status": "PERMISSION_DENIED",
    "details": [
      {
        "@type": "type.googleapis.com/google.rpc.Help",
        "links": [
          {
            "description": "Google developer console API key",
            "url": "https://console.developers.google.com/project/[MyProjectId]/apiui/credential"
          }
        ]
      }
    ]
  }
}

I have: "firebase": "^7.6.1" "react": "^16.12.0"