Starting this week, the default model for ChatGPT free users and Go plan subscribers will be sequentially changed to GPT-5.6 Luna. Luna is a model with lower performance than Sol or Terra.
Starting next week, you will be able to use text conversations unlimitedly, and a new 'Think' button will also be provided for asking difficult questions. Pressing this button allows Luna to infer.
However, other tools such as file upload and image functions still have limitations when used.
https://help.openai.com/en/articles/6825453-chatgpt-release-notes
Users subscribing to the higher-tier Plus and Pro plans will be able to use the updated GPT-5.6 Sol model in ChatGPT, and a new inference slider will also be sequentially provided.
The updated GPT-5.6 Sol is a model for everyday conversations, so it is said that it will only be available in ChatGPT's Chat mode. Therefore, it does not apply to Work mode and Codex.
