The error message displayed when a model refuses a request for safety reasons was reworded. Previously the wording varied based on category ("cybersecurity or biology topics" vs "sensitive topics"); it now consistently reads: "[Model] has safety measures that flag messages on most cybersecurity or biology topics (https://www.anthropic.com/legal/aup). They may flag safe, normal content as well. These measures let us bring you Mythos-level capability in other areas sooner, and we're working to refine them."
Evidence
Updated refusal error renderer (search for "has safety measures that flag messages on most cybersecurity or biology topics")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.