OpenAI's GPT-5.3 Instant — the company's most widely used model — reduces hallucinations by up to 26.8% compared to its predecessor, prioritizing accuracy and conversational reliability over raw performance gains, OpenAI says.GPT-5.3 Instant, which is essentially the default and is the most used model for ChatGPT users, also improves on tone, relevance and conversation with fewer refusals. It is available on both ChatGPT and on the API. Right now, only the Instant model will be upgrade...