OpenAI has adjusted the behaviour of its most-used ChatGPT model, `GPT-5.5 Instant`. According to OpenAI's help article, **GPT-5.5 Instant** is the default for all logged-in users and can automatically switch to `GPT-5.5 Thinking` for harder tasks (OpenAI Help Center). 9to5Mac reports a recent tweak described by OpenAI as making the model "much more fun to talk to" and better at understanding intent, handling complex constraints, and giving more cohesive shopping and local recommendations (9to5Mac). OpenAI's April blog introduced `GPT-5.5` as a higher-capability family for coding, reasoning, and tool use (OpenAI blog). Editorial analysis: For practitioners, the change is an incremental UX and routing improvement rather than a new capability tier, but it may affect prompt behaviour and testing baselines.