AI adoption
DeepSeek is the Chinese developer of low-cost artificial intelligence models whose API is used by companies worldwide. On 10 September 2026, it announced DeepSeek-V4.1-Flash, a model with 552 billion parameters, of which 8 billion are active on input and 16 billion on output, with image understanding, available under the name deepseek-flash. The same note states that the former names deepseek-v4-flash and deepseek-v4-flash-vision-exp are “temporarily” routed to V4.1-Flash for compatibility, that the corresponding models are retired, and that V4-Pro, the top-of-the-range model, is being retired. Since 14 September 2026 at 04:00 UTC, requests sent to deepseek-v4-pro have been served by V4.1-Flash, “until the launch of V4.1-Pro”. The new prices have applied since 10 September at 04:00 UTC. They appear only in an image, and off-peak hours cost half the peak rate. The note does not say whether responses flag the redirection, or when V4.1-Pro will arrive.
Our perspective
A customer who validated its workflows on V4-Pro has, for a month, been receiving answers from another model, under the same name, at the Flash price. The cost saving is real, a drop in quality is possible, and the developer decides how long it lasts. A model’s name in a contract or a procedure guarantees nothing. Only a rerun evaluation set detects the change. Our advice: for each model the company calls, record the date of its last evaluation and rerun it as soon as a developer note mentions a redirection.
Interested source: the developer describes its own redirection. Prices are shown only as an image in the source and are not reproduced here.
Sources
DeepSeek, note of 10 September 2026, “DeepSeek-V4.1-Flash: Smarter, Faster, More Efficient”, accessed 17 October 2026: https://api-docs.deepseek.com/news/news260910 · DeepSeek, API news, accessed 17 October 2026: https://api-docs.deepseek.com/news/
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