But, the web ui chat version of flash has very poor language following abilities in my experience:

You may ask it something in English, and get a thinking chain in Chinese with an answer in Chinese, or an English thinking chain and an English answer. Using the retry button on the same question has a 50/50 chance of any of those results.

Sometimes, asking something in English, but where information are mostly in another language may make the answer in the language where data has been found. The other day, I asked something about a local German thing, in English, and I got an answer in German instead. It’s as if all the language data stirred it away from the language of the user’s question.

all requests to the Pro model will be routed to V4.1 Flash and billed at Flash's price

If I'd carefully tested and optimized prompts against Pro I wouldn't be keen on this particular news. I feel like API model providers should lean towards not swapping out models on their paying customers, no matter how much "better" the new model is meant to be.

In keeping with our commitment to user responsibility, following the official launch of V4.1 Flash and prior to the release of V4.1 Pro, all requests to the Pro model will be routed to V4.1 Flash and billed at Flash's price

Please don't do this kind of thing. If a user has validated a workflow on V4 Pro, they might not want to suddenly start testing it in production on V4.1 Flash. Instead, keep V4 Pro around but deprecated for a defined period of time, then remove it.

At least as open weights models, it's possible to use something like Together.ai or OpenRouter to run the V4 Pro model as long as other providers keep it up.

For all intents and purposes, "low" is pretty much the same as turning reasoning off, and "high" is similar to "max". "High/max" performs way too much reasoning, takes forever, and causes costs to balloon. They need a proper "medium" setting.

I get it that they're probably focused on pushing performance right now, but the ergonomics of the model aren't great.

https://www.geeky-gadgets.com/deepseek-v4-1-flash-review/

I hope some of those speed increases will make it to production.

I wonder if this comes from using the bad architecture scaled up (and it hits some limits) or if this is a data problem (undertrained? bad data? bad pre-processing using smaller models?)...

I was getting something like 300-400 tok/s which was just insanity. It was running so much faster than the toolcalls themselves. Honestly, even if it's not quite as strong in reasoning, it just throws so much so fast that it can do a lot more than you might expect.

I'd say it was comparable with GLM5.3 Flash.

At these prices, you can start throwing Flash at a lot of small, repetitive tasks where you wouldn't even consider using a bigger model before. It feels like the interesting shift is not “Flash replaces Pro”, but “there are now a lot more things worth automating.”

I also find the DeepSeek models to be more precise than Claude models (last I used 4.7) in that I yet had not the occasion where model did something unintentional that I did not direct it to.

EDIT: Updated percentage reduction.

hope deepseek makes me change my setup again

Looks like the new model can be used if summoned via the API but the API won't list it.

As a consumer I feel like hansel and gretel combined, deepseek could be the witch.

Fairly excited for the v4.1 launch. Input cache hit prices have been halved, which looks nice.

It’s good and very fast.

(Note that the deepseek API trains on your data)

    In keeping with our commitment to user responsibility, following the official launch of V4.1 Flash and prior to the release of V4.1 Pro, all requests to the Pro model will be routed to V4.1 Flash and billed at Flash's price.

all requests to the Pro model will be routed to V4.1 Flash and billed at Flash's price

While V4.1 Flash performance and cost looks promising this auto re-routing sounds concerning

In keeping with our commitment to user responsibility, following the official launch of V4.1 Flash and prior to the release of V4.1 Pro, all requests to the Pro model will be routed to V4.1 Flash and billed at Flash's price. If you encounter any issues during your comparative testing between V4 Pro and V4.1 Flash, please do not hesitate to reach out to us with your feedback. Thank you for your support!

Wow. Imagine OpenAI/Google/Anthropic doing this! Nope.

You'd think it would have been something they did a year ago, but here we are. Still.