Free ChatGPT users shouldn't notice much of a change, but some devoted 4o users are already clearly disgruntled.
It's been framed as part of a broader model lineup refresh timed with “the previously announced retirement” of GPT-5 (Instant and Thinking) within ChatGPT.
OpenAI has announced it will retire GPT-4o, GPT-4.1, and other models from ChatGPT on February 13, marking its second attempt after user protests forced reversal.