What does the "403 access_denied" error signify when integrating Home Assistant with Google services?

The "403 access_denied" error indicates that the Google API rejected Home Assistant's request because the credentials provided are insufficient or invalid. This means the Google Cloud Project (GCP) or the associated account lacks the necessary permissions, the authentication token is expired, or the request itself violates Google's security policies for that specific API, preventing Home Assistant from accessing the requested Google resource.