Testing version name: deepseek-v4.1-flash-expires-on-0910. DeepSeek is reportedly planning to officially release its V4.1 Flash model around September 10, 2026 (Beijing Time). According to internal and external testing, said DeepSeek, V4.1 Flash has outperformed V4 Pro across key metrics, including performance, cost, generation speed, and overall completion time. After V4.1 Flash is officially launched and before V4.1 Pro becomes available, requests to V4 Pro will be routed to V4.1 Flash instead and billed at the V4.1 Flash rate. DeepSeek is also asking users to report any issues identified when comparing V4 Pro and V4.1 Flash.