Anthropic's watermark rollout leaves a loophole on two older Claude models
Anthropic is expanding its text watermark to four more Claude models ahead of the EU AI Act's December deadline. On the older Claude Opus 4.6 and Sonnet 4.6, however, developers can bypass the watermark by tweaking a single sampling parameter, and Anthropic has addressed the gap with only a compliance warning. This matters because watermarking is a key transparency measure under EU rules, and a trivial bypass on older models weakens its reliability as a provenance signal.
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- The Decoder2026-10-31 19:20