Copilot start a new session and consume tokens automatically

- Copilot Chat Extension Version: built in
- VS Code Version: 1.134.0
- OS Version:Ubuntu 24.04
- Feature (agent mode):
- Selected model (any):
- Logs: None

Steps to Reproduce:

1. Choose Plan to generate any plan.
2. Choose 'Autocopilot' to run the Plan. Wait to finish.
3. Click the `<-` to back to the session list, or click the "+" to create a new session.
4. with about 70%~80% chance, the Copilot start a new session and add "Start implementation" as a normal chat message and start to run the agent automatically.

It's a huge waste of tokens! Hope someone fix this quickly.
I found this from 1.130.0 , and maybe it exists earlier.