The article suggests that ChatGPT slows down because it is winter and in the winter people (and data on which ChatGPT trained) sometimes slow down: the dark/gloomy/depressing winter feeling. To which I made the statement that ChatGPT does not know that it is winter so the hypothesis in the linked article does not hold up.

Several people have commented that ChatGPT does know the current time and date, so maybe there is indeed some truth in the linked article. But it does show how inconsistent ChatGPT can be: in any interaction I had with it I could not get CHatGPT to admit that it knew the current time, date, or season.