Anthropic's launch of Claude Fable 5 has included a bit of backlash as the company would downgrade to Opus 4.8 depending on the query such as cybersecurity and sensitive topics. In a post, Anthropic said it will visibly show the switch to Opus 4.8. That won't be enough to satisfy everyone, but at least it's more transparent.
By default, automatic model switching is active in Claude, Claude Cowork, Claude Code, Claude Design, and Claude for Microsoft 365. In this case, Claude re-runs your blocked Claude Fable 5 request on Claude Opus 4.8 in the same conversation. You’ll see a notice explaining that the model switched, and the response will be labeled with the model that answered. Opus is a highly capable model with strong safeguards of its own, and for most otherwise legitimate requests blocked on Fable 5—including most biology questions—Opus should give you a helpful answer.
After the switch, the model picker stays on Opus for the rest of the conversation. You can switch back to Claude Fable 5 anytime from the model picker.
See: Anthropic’s Claude Fable 5, Mythos 5: What you need to know