[Bug] Model unexpectedly reverted from Claude 5 fable to Claude 4.8 opus

Question

**Bug Description**
the model mistakenly switched back to opus 4.8 from fable 5. You are allowed to take a look on my output/methods_v5.tex, there is nothing sensitive!

**Environment Info**
- Platform: linux
- Terminal: gnome-terminal
- Version: 2.1.198
- Feedback ID: 5a9c12a3-6982-4ddf-9169-aaeb27c82713

**Errors**
```json
[]
```