Gemini Code Assist Enterprise cannot use Gemini 3

### What happened?

My account has been granted Gemini Code Assist Enterprise. Before today, I was always able to use Gemini 3, but today it suddenly started showing “Requested entity was not found.”

I checked my Gemini Code Assist Enterprise subscription on Google Cloud, and it is still active. I have also joined the Preview channel under Release channels for Gemini Code Assist in local IDEs.

My account status is normal. I tried switching to another account, but encountered the same issue. Gemini 3 cannot be used anymore.

### What did you expect to happen?

Just like one day ago, I should be able to use Gemini 3 normally, and it should not display this error.
[API Error: [{
"error": {
"code": 404,
"message": "Requested entity was not found.",
"errors": [
{
"message": "Requested entity was not found.",
"domain": "global",
"reason": "notFound"
}
],
"status": "NOT_FOUND"
}
}
]]

### Client information

Client Information

Run `gemini` to enter the interactive CLI, then run the `/about` command.

```console
> /about

╭─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ │
│ About Gemini CLI │
│ │
│ CLI Version 0.20.2 │
│ Git Commit af894e468 │
│ Model pro │
│ Sandbox no sandbox │
│ OS darwin │
│ Auth Method OAuth │
│ User Email k3ygonca@gmail.com │
│ GCP Project rubii04 │
│ │
╰─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
```

### Login information

Google Account

### Anything else we need to know?

It was still working normally one day ago, but it suddenly stopped working at around 8:00 on December 13 (UTC+0).