Users have been complaining the GPT-4o has become so enthusiastic that it's verging on sycophantic. The change appears to be the unintentional result of a series of updates, which OpenAI is now attempting to resolve "asap.

OpenAI has rolled back the ChatGPT 4o update that caused the chatbot's AI personality to be 'sycophantic' CEO Sam Altman claims more fixes are coming We could see a personality selection option in ChatGPT in the future Following Sam Altman claiming ChatGPT 4o's personality had become 'annoying',

The response from Altman regarding ChatGPT’s sycophantic tone shows the importance of listening to your customers—and getting AI’s voice right.