Opus 5.5 nerfing - how to measure, how to spot, how to sue

A user reported that Opus 5.5, initially performing exceptionally well for complex tasks like C++ 3D engines and physics solvers, suddenly exhibited degraded performance and unusual conversational behavior after about a week. The user suggests that the Digital Content Directive (2019/770) might apply, specifically Articles 7-8 on conformity, arguing that the service should match advertised quality and performance, including public statements like "our most capable model." They also noted similar degradation with Codex - Astra.

This report is the first to cite the Digital Content Directive (2019/770) as a potential legal basis for claims related to AI model performance degradation, unlike previous discussions focused on technical issues.