Anecdotally, it's quite clear that some models are throttled during the day (eg Claude sometimes falls back to "concise mode" - with and without a warning on the app).
You can tell if you're using Windsurf/Cursor too - there are times of the day where the models constantly fail to do tool calling, and other times they "just work" (for the same query).
Finally, there's cases where it was confirmed by the company, like Gpt-4o's sycopanth tirade that very clearly impacted its output (https://openai.com/index/sycophancy-in-gpt-4o/)
Trusting these LLM providers today is as risky as trusting Facebook as a platform, when they were pushing their “opensocial” stuff
You've also made the mistake of conflating what's served via API platforms which are meant to be stable, and frontends which have no stability guarantees, and are very much iterated on in terms of the underlying model and system prompts. The GPT-4o sycophancy debacle was only on the specific model that's served via the ChatGPT frontend and never impacted the stable snapshots on the API.
I have never seen any sort of compelling evidence that any of the large labs tinkers with their stable, versioned model releases that are served via their API platforms.
> At the time of writing, there are two major versions available for GPT-4 and GPT-3.5 through OpenAI’s API, one snapshotted in March 2023 and another in June 2023.
openaichat/gpt-3.5-turbo-0301 vs openaichat/gpt-3.5-turbo-0613, openaichat/gpt-4-0314 vs openaichat/gpt-4-0613. Two _distinct_ versions of the model, and not the _same_ model over time like how people like to complain that a model gets "nerfed" over time.
When a new model comes out I test the waters a bit with some more ambitious queries and get impressed when it can handle them reasonably well. Over time I take it for granted and then just expect it to be able to handle ever more complex queries and get dissappointed when I hit a new limit.
Which is why the base model wouldn't necessarily show differences when you benchmarked them.
Like I suspect if there was a "new" model which was best-of-256 sampling of gpt-3.5-turbo that too would seem like a really exciting model for the first little bit after it came out, because it could probably solve a lot of problems current top models struggle with (which people would notice immediately) while failing to do lots of things that are a breeze for top models (which would take people a little bit to notice).
You pay monthly fee, but Gemini is completely jammed 5-6 hours when North America is working.
Google is best in pure AI research, both quality and volume. They have sucked at productization for years. Not not just AI but other products as well. Real mystery.
There are tons of benchmarks that don't show any regressions. Even small and unpublished ones rarely show regressions.
Now I'm feeling similarly with their image generation (which is the only reason I created a paid account two months ago, and the output looks more generic by default).
This time around it felt pretty stark. I used ChatGPT to create at most 20 different image compositions. And after a couple of good ones at first, it felt worse after. One thing I've noticed recently is that when working on vector art compositions, the results start more simplistic, and often enough look like clipart thrown together. This wasn't my experience first time around. Might be temperature tweaks, or changes in their prompt that lead to this effect. Might be some random seed data they use, who knows.