`az functionapp keys list` throws 'Bad Request'

## Describe the bug

**Command Name**
`az functionapp keys list`

**Errors:**
```
Operation returned an invalid status 'Bad Request'
```

The app name and resource group are correct since `az functionapp show -g {} -n {}` with the same values works.

## To Reproduce:
- Linux Function App v4.
- Configured to pull container image from Azure Container Registry using managed identity.
- Storage Account has been created with `--public-network-access Disabled`.
- `az functionapp keys list -g {} -n {}`

## Expected Behavior
- Lists the keys (or shows an empty list like I would've expected in this particular case) or
- more informative error message.

## Environment Summary
```
Linux-4.4.0-19041-Microsoft-x86_64-with-debian-bullseye-sid, Ubuntu 20.04 LTS
Python 3.6.10
Installer: DEB

azure-cli 2.31.0

Extensions:
aks-preview 0.5.49
```

## Additional Context