Error: HTTP error 504 with body: stream timeout in MLS validation

<img width="843" height="516" alt="Image" src="https://github.com/user-attachments/assets/98d387c5-6847-4891-a88e-f2ada0ff98fc" />

```
rpc error: code = InvalidArgument desc = HTTP error 504 with body: stream timeout
```

This identity will now be missing.

It is probably a temporary disconnection between the MLS validation service and the indexer process. This should be retryable.