@simon it was also shared on /r/claudeai where a substantial portion of the community are convinced sonnet 3.5 has degraded significantly in recent weeks. https://old.reddit.com/r/ClaudeAI/comments/1f1shun/new_section_on_our_docs_for_system_prompt_changes/
Per the rep "We've also heard feedback that some users are finding Claude's responses are less helpful than usual. Our initial investigation does not show any widespread issues. We'd also like to confirm that we've made no changes to the 3.5 Sonnet model or inference pipeline."