What does Lu Xun mean by "Today's weather is hahaha"?

Under the pressure of literary inquisition, people are in a situation where they can neither say good nor dare to say bad when facing something.

Even if you meet and chat, you can only say half a sentence. What is the weather like today? Dare not judge, can only use hahaha to replace and omit. It typically describes the living environment and state of the people at that time, and also cleverly satirizes the darkness of the society at that time.