During the evening, my TUI instances regularly get transient API errors

### Describe the bug
● Request failed due to a transient API error. Retrying...
● Request failed due to a transient API error. Retrying...
● Request failed due to a transient API error. Retrying...
● Request failed due to a transient API error. Retrying...
● Request failed due to a transient API error. Retrying...
✗ Execution failed: Error: Failed to get response from the AI model; retried 5 times (total retry wait time: 27.10 seconds
Last error: CAPIError: 503 {"error":{"message":"HTTP/2 GOAWAY connection terminated","type":"connection_error"}}

### Affected version

GitHub Copilot CLI 1.0.40.

### Steps to reproduce the behavior

Use it after 8pm PST.
no other apps experience network issues.

### Expected behavior

N/A

### Additional context

It seems to occur when in /plan mode

The report names GitHub Copilot CLI 1.0.40, TUI use, and /plan mode but no source files or tests. Start by reproducing the failure after 8pm PST in /plan mode, then trace the transient API retry and HTTP/2 GOAWAY handling; done means the reported requests no longer fail repeatedly under those conditions.

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