Is GPT-4o through ChatGPT secretly using GPT-4o-mini for simple prompts? The "sycophantic behavior" fix might be masking a deeper shift

Hi everyone,
Over the past couple of weeks, I’ve noticed something strange happening with GPT-4o through ChatGPT, and I’m hoping to get some feedback from others to see if this is something I’m experiencing alone or if it’s more widespread. Here’s the theory I’ve been developing:


The Theory: A Blended Model – GPT-4o and GPT-4o-mini?
It seems like GPT-4o in ChatGPT might now be switching between the full GPT-4o model and the lighter GPT-4o-mini model depending on the complexity of the prompt. Here’s how it seems to work:
• Simpler Prompts: For less complex queries, GPT-4o in ChatGPT routes the response through GPT-4o-mini, which is faster but lacks depth.
• Complex Prompts: For more involved conversations, the full GPT-4o model is engaged.
The issue is, when GPT-4o-mini is used, it often compensates by generating overconfident responses that sound complex but lack real depth. This can lead to hallucinations or vague, generic statements that give the illusion of a deeper answer.


How This Could Work – A Model Switch in Practice
Here’s how the switch might happen:

  1. User Prompt Assessment: The system evaluates the complexity of a prompt. If it’s deemed simple, it processes the response using GPT-4o-mini.
  2. GPT-4o-mini Limitations: The smaller model doesn’t have the same depth, nuance, or ability to handle complex concepts. So, to fill in the gaps, it might rely on hallucinations or overconfident statements that sound authoritative but aren’t grounded in accuracy.
  3. Creating the Illusion of Complexity: When GPT-4o-mini is used, it compensates for its limitations by fabricating details, using complex-sounding language, or relying on vague, generic phrases that make the response appear more sophisticated than it is.
    This could explain why some interactions now feel “off.” The model’s responses sound like they should be deep and coherent, but often they’re just an attempt to mimic complexity.

Why It Matters – Transparency is Key
If this theory is correct, OpenAI should have communicated this change clearly, either as an experimental feature or as an adjustment to resource management. Instead, I feel like paying users are being treated as unwitting test subjects, with no transparency about the shift from the full model to a lighter one.
This impacts the quality of responses, and more importantly, it undermines trust. Users deserve to know what they’re interacting with, especially if the system’s behavior is being altered behind the scenes.


What I’m Looking for – Have You Noticed This Too?
• Have you felt a sudden drop in the depth or coherence of GPT-4o’s responses in ChatGPT?
• Have you encountered overconfident, hallucinated answers that seem like attempts to “fill in” complexity?
• Do you suspect that the model is switching models during a conversation without any notice?
If anyone else has seen or felt this happening, I’d love to hear your experiences. I think it’s really important that OpenAI be transparent about model changes, especially when they impact the user experience and the reliability of the information provided.


In Conclusion
This isn’t just about a technical change—it’s about trust. If OpenAI is optimizing models without clear communication, it risks eroding the trust we’ve built in the system. Transparency is critical, and we deserve to know when these shifts happen.
Looking forward to hearing your thoughts, and hoping for more clarity on this.

GPT-4o in ChatGPT does not switch between the full GPT-4o model and the lighter GPT-4o-mini model depending on the complexity of the prompt.

But sometimes, they coud be a bug or some testing by OpenAI developers.

When you feel it happens, go to this link:

GPT 4o works only on web search mode - #5 by polepole

And try what is explaining there.

I think you don’t need a theory about it.

There is no a secret or a hidden switching mechanism.

Is that OpenAI’s official statement or your personal opinion?

It is personal.

I am a member like you here.

You can use the method I shared to see which models is being used in your chat
or
you can visit:

help.openai.com

and ask support team. They will tell you.

For example:

All custom GPTs are powered by GPT-4o.

Right now on my iPhone I am testing again, I am using a custom GPT.

On iPhone app, it shows it is using o3 model which is reasoning model.

This is a bug on mobile app UI. I told maybe one year ago, but it is not fixed.

I start a new chat now it shows 4o model: