Vertex gemini 2.0 models failing to connect with 404 in one cloud instance while works great in another

Vertex Gemini 2.0 model suddenly started to fail since 4am IST in a specific us-central1 cloud instance.

locations/us-central1/publishers/google/models/gemini-2.0-flash` was not found or your project does not have access to it. Please ensure you are using a valid model version. For more information, see: Model versions and lifecycle  |  Generative AI on Vertex AI  |  Google Cloud Documentation , Status: NOT_FOUND,

However works in our lower environment . This is a sudden outage with no changes made to production GCP cloud instance at all.

What should we be checking?