Models don't know what their cutoff dates are unless told via a system prompt.
The proper way to figure out the real cutoff date is to ask the model about things that did not exist or did not happen before the date in question.
A few quick tests suggest 5.5's general knowledge cutoff is still around early 2025.
OpenAI does tell the model the current date via API, so it's odd for them not to also tell the model its cutoff
Stupid question: wouldn't it then search the web for that event?
i wonder if they put an older cutoff date into the prompt intentionally so that when asked on more current events it leans towards tool calls / web searches for tuning