The name stayed
Calls to DeepSeek V4 Pro reach a different model from Monday, and DeepSeek’s own card shows what it is worse at
At 04:00 UTC on 14 September the name deepseek-v4-pro starts returning V4.1 Flash at under a quarter of the price. Neither DeepSeek’s pricing page nor its change log offers a way to keep the old model.
| Route and name | Model that answers | Input, per M | Output, per M |
|---|---|---|---|
| DeepSeek API, deepseek-v4-pro, until Monday | V4-Pro-0813 | $0.66 | $1.98 |
| DeepSeek API, deepseek-v4-pro, from Monday | V4.1 Flash | $0.15 | $0.60 |
| OpenRouter, deepseek-v4-pro, 15 hosts | V4 Pro 0423 | $0.87 to $2.00 | $1.20 to $4.00 |
| OpenRouter, deepseek-v4-pro-0813, 18 other hosts | V4-Pro-0813 | $0.99 to $1.45 | $2.60 to $4.36 |
DeepSeek pointed two retired model names at its new V4.1 Flash on Thursday, the day it released the model. Anyone still calling deepseek-v4-flash has been answered by V4.1 Flash since, at the new rate.
On Monday the same rule reaches V4 Pro, DeepSeek’s largest model, and that is the change that matters. A DeepSeek model name now buys a price tier, not a set of weights.
The mechanism is a footnote on the pricing page. From 12:00 Beijing time on 14 September, “and until V4.1 Pro is released in the future, requests to deepseek-v4-pro will all be routed to V4.1 Flash and billed at the V4.1 Flash price.” The endpoint does not change and neither does the request.
What answers it does. DeepSeek’s card lists V4 Pro at 1.6 trillion backbone parameters, against 552 billion for V4.1 Flash, an encoder-decoder that activates 8 billion of them while it reads a prompt. It can, because its decoder’s cache is projected from the encoder’s final layer instead of being computed afresh at every layer.
For a V4 Pro customer the bill falls by roughly three quarters: off-peak input drops from $0.66 per million tokens to $0.15. The concurrency ceiling rises fivefold.
V4 Flash customers got a smaller cut on Thursday. DeepSeek’s page as it stood on 9 September listed V4 Flash input at $0.22 per million off-peak, against $0.15 now.
DeepSeek’s case is that nobody loses anything. Its change log says V4.1 Flash has “comprehensively surpassed V4 Pro in performance, cost, speed, and total time.” Its own model card, published the same day, does not support the first of those words. On the card’s base-model table V4 Pro scores 55.2 on SimpleQA-Verified, a test of short factual recall, against 42.3 for its replacement. It also leads, by smaller margins, on the long-context LongBench-V2, on GPQA Diamond and on the text-only Humanity’s Last Exam. So the claim fails for retrieval, factual answering and long documents.
It holds for agents that write and run code, and that is why DeepSeek can make it at all: V4.1 Flash scores 30.0 on Terminal-Bench 3.0 against V4 Pro’s 11.8. The footnote reroutes both kinds of traffic alike.
| Benchmark | V4 Pro | V4.1 Flash |
|---|---|---|
| SimpleQA-Verified, short facts | 55.2 | 42.3 |
| LongBench-V2, long context | 51.5 | 45.2 |
| GPQA Diamond | 92.4 | 90.9 |
| Humanity’s Last Exam, text only | 42.7 | 39.1 |
| DeepSWE v1.1, resolved | 62.7 | 74.2 |
| Terminal-Bench 3.0 | 11.8 | 30.0 |
The string was never one model to begin with. On OpenRouter, deepseek/deepseek-v4-pro is labelled V4 Pro 0423 and served by fifteen third-party hosts, nine of them at FP8 and two at FP4, while a separate slug carries the 0813 checkpoint DeepSeek’s own API has been serving. OpenRouter marks its one floating DeepSeek name with a tilde, ~deepseek/deepseek-v4-flash-latest, and says it “always redirects to the latest model”. DeepSeek’s API gives no such mark to a name that now floats.
Nor are the weights the whole system. On DeepSeek’s scaffold table the same V4.1 Flash weights resolve 74.2 per cent of DeepSWE tasks under mini-SWE and 65.5 per cent under OpenCode, a spread of almost nine points from the harness alone.
The verdict: if deepseek-v4-pro is pinned anywhere, run your evaluation set against deepseek-flash before 04:00 UTC on Monday, while the old model can still be called beside it on the same key. Coding-agent traffic gets cheaper and, on DeepSeek’s numbers, better. Retrieval and long-document work is where those numbers point the other way, and the exit for it is a third-party host serving the 0813 weights, listed on OpenRouter at $0.99 to $1.45 per million input tokens.
Leave DeepSeek itself out of that route. It is one of the nineteen providers OpenRouter lists for the 0813 slug, at $0.66 against $0.99 and up for the other eighteen, and neither page says whether it will still serve 0813 there once its own API stops on Monday.
What it changes Search code, configs and gateway routing tables for the string deepseek-v4-pro today: anything that matches changes model at 04:00 UTC on Monday whether or not you deploy. On OpenRouter, give the 0813 slug a provider order that leaves DeepSeek out until its listing says what it serves.
Every benchmark figure is DeepSeek’s own, from its model card, and none has been run independently. The V4 Flash rates before Thursday come from DeepSeek’s pricing page as archived on 9 September. OpenRouter’s prices and host counts were read from its API on 11 September and change without notice.
Primary source read
DeepSeek Models & Pricing DeepSeek API change log, 10 September DeepSeek-V4.1-Flash model card DeepSeek pricing page as archived 9 September OpenRouter: DeepSeek V4 Pro 0813