Continuous Firebase Authentication Error in WebApp

I have been trying to deploy and run a simple Firebase Cloud Function. Every attempt fails due to what appears to be a fundamental issue with service account creation and authentication context in my project.

Symptoms:

1. When calling the function, the context.auth object is always null or undefined, even when the client sends a valid, verified ID token. The function logs show The function must be called while authenticated.
2. During deployment, I am now receiving the error: Error: Error generating the service identity for pubsub.googleapis.com.

We have already verified the following:

• The project is linked to an active billing account.
• All necessary APIs are enabled (Cloud Functions, Cloud Build, Run, Artifact Registry, IAM, etc.).
• We have tried manually adding IAM service accounts and toggling the Cloud Functions API off and on.
• We have removed all restrictions from the browser API key.

The project seems unable to correctly manage its own service identities and pass authentication context to its services.