The paper proposes and evaluates "model verification" methods to detect these "fakes":
The study identified . These services are significantly popular in the academic and developer communities; as of late 2025, they had accumulated over 58,000 GitHub stars and were cited in 187 academic papers . 2. Deceptive Model Claims Shadow Cheats API
: Analyzing specific patterns in model output to verify its identity. as of late 2025
: Users treating these as interchangeable substitutes often suffer from degraded output quality without realizing the model is not the official one. 3. Security and Supply Chain Risks they had accumulated over 58
This paper addresses the fundamental opacity of the "Shadow API" market where platforms claim to provide the same output as official LLMs via unauthorized, indirect access.