Can you share an example chat or prompt?
Then I could see whether I can reproduce it on my ChatGPT Plus account.
Or which model OpenAI claims it to be from.
On the website, you can use the following CSS to show which LLM, OpenAI claims to have used:
https://chatgpt.com/share/69371729-f090-8004-b69b-aa9f25ca0b40 here is a recent, but not very bright example, since it did finish the task after all (it used to completely ignore the most recent task in other cases). After thinking it answered “Yes” again, even though second prompt does not contain a question.
I slightly incorrectly posed a question and did not explain what i meant by abundancy, but i feel that is not a problem, since chat has this behaviour in any conversation it uses deep-thinking mode.
It claims to be 5.1, I do not know how to check it
The first response is claimed to by gpt-5-1.
The second response is claimed to by gpt-5-1-t-mini (thinking for 5 seconds).
there is no version selection.
If I switch to a free ChatGPT account, I can still select “Thinking” on the website by click on the plus next to the input box. That then routes me to gpt-5-1-t-mini.
Alternatively you can append “think hard” to your prompt, which will usually route you to gpt-5-1-t-mini too. I tried this with your prompt and it worked.
If you want to try your prompt against frontier LLMs, you could try LMArena. Your prompt will be shared with researchers and trained on, but you can try gpt-5.1-thinking-high, opus-4.5-thinking and gemini-3-pro-preview for free. The Gemini App and Google AIStudio also give free access to gemini-3-pro-preview. Or you buy a subscription.
Can you share an example chat or prompt? Then I could see whether I can reproduce it on my ChatGPT Plus account. Or which model OpenAI claims it to be from.
On the website, you can use the following CSS to show which LLM, OpenAI claims to have used:
(I like this Chrome extension for adding JavaScript and CSS to pages.)
https://chatgpt.com/share/69371729-f090-8004-b69b-aa9f25ca0b40 here is a recent, but not very bright example, since it did finish the task after all (it used to completely ignore the most recent task in other cases). After thinking it answered “Yes” again, even though second prompt does not contain a question.
I slightly incorrectly posed a question and did not explain what i meant by abundancy, but i feel that is not a problem, since chat has this behaviour in any conversation it uses deep-thinking mode.
The first response is claimed to by
gpt-5-1. The second response is claimed to bygpt-5-1-t-mini(thinking for 5 seconds).If I switch to a free ChatGPT account, I can still select “Thinking” on the website by click on the plus next to the input box. That then routes me to
gpt-5-1-t-mini. Alternatively you can append “think hard” to your prompt, which will usually route you togpt-5-1-t-minitoo. I tried this with your prompt and it worked.Note: with free ChatGPT the context window of your
gpt-5-1is limited to 16k tokens.If you want to try your prompt against frontier LLMs, you could try LMArena. Your prompt will be shared with researchers and trained on, but you can try gpt-5.1-thinking-high, opus-4.5-thinking and gemini-3-pro-preview for free. The Gemini App and Google AIStudio also give free access to gemini-3-pro-preview. Or you buy a subscription.