It is a metaphor for reports that have lost their news value or things that have lost their timely effect.
From: Don’t rush back when we meet again, the yellow flowers and butterflies will be worried tomorrow. ——Su Shi's "Nine Days with Wang Gong"
The bees and butterflies don't know when the festival is gone, and the broken branches are still twisting around the dawn court. Since today's hearts are different, the autumn frost has not faded overnight.
——"Ten Days Chrysanthemum" by Zheng Gu of the Tang Dynasty