OpenAI to Retire GPT-4o, GPT-4.1, GPT-4.1 mini, and OpenAI o4-mini in ChatGPT by Tomorrow > Says feedback from GPT-4o users helped shape GPT-5.1/5.2 with improved personality. > “We’re announcing the upcoming retirement of GPT‑4o today because these improvements are now in place, and because the vast majority of usage has shifted to GPT‑5.2”