China startup Deepseek's V4 fails to close the AI capability gap with frontier US models, despite offering high performance at a lower cost. "V4 performance falls marginally short of GPT-5.4 and Gemini-3.1-Pro, suggesting a developmental trajectory that trails state-of-the-art frontier models by…3 to 6 months," Deepseek said. V4 series supports text only, unlike many of its closed-source peers.