Anthropic said on October 12 that new safeguards against distillation attacks — campaigns that systematically probe a model to copy its capabilities — have cut the data harvested from Claude by about 90% to 99%. The company said the volume of reasoning tokens extracted by distillers is now far lower than before the measures were introduced.

The defences restrict access to Claude's protected reasoning and aim to block extraction attempts run through proxy networks at scale. Anthropic said it has banned tens of thousands of accounts linked to distillation campaigns and named Z.ai, also known as Zhipu, as an example it linked to attempts involving its GLM-5.3 work.

There is a trade-off for legitimate users. Coverage of Anthropic's own post notes a reported false-positive rate below 0.1%, but says some benign API requests can still be blocked, some integrations have needed changes, and certain blocked requests may still be charged. The figures are Anthropic's own reported measures, not independent verification that distillation has stopped.