Don’t ask ChatGPT what model it uses. Besides the AI not answering correctly, the GPT instructions could tell the AI it actually runs “Anthropic Claude” and provide you with further misinformation.
GPTs will always run gpt-4o now, regardless of the subscription tier.
Whether you get a few GPT trials in a free ChatGPT account, or pay for a $200/mo pro subscription, that same gpt-4o model version is used for GPTs. The model cannot be chosen by you.
It was an instant switch from the gpt-4-turbo ChatGPT was previously using (what ChatGPT still calls “GPT-4”) to gpt-4o that broke the functionality of many GPTs overnight. Similarly, a user switching the model themselves to a better or worse one would only cause more headaches for the GPT developer.