"The model you've selected is experiencing high load. Please switch to another model" on Claude Sonnet 4

## System details (run `AWS: About` and/or `Amazon Q: About`)

- OS:
- Visual Studio Code version:
- AWS Toolkit version:
- Amazon Q version:

## Question

The Claude Sonnet 4 model keeps sending me "The model you've selected is experiencing high load. Please switch to another model" although I have tried uninstalling/re-installing Amazon Q / VS Code. Quitting the IDE. I have also subscribed to the Pro cause I thought chat is limited.

Start by collecting the missing OS, Visual Studio Code, AWS Toolkit, and Amazon Q versions using the listed AWS: About and Amazon Q: About commands. Reproduce the Claude Sonnet 4 high-load message and determine whether it is an Amazon Q or AWS service issue; the report is not complete until the cause and an actionable fix or escalation path are documented.

Written by the indexing model from the issue text.