It's funny as a parody of newspaper articles, but it pretty much just took a "breaking news" article format and stuck in specifics about leaves and trees. Which, again, is pretty funny and I enjoyed reading it, but articles in The Onion are typically much more satirical.

A satire writer would have used this premise to express a point of view. Bad example but if you were critical of climate change predictions you could use that premise to satirize climate change predictions: "Leaf falls from tree. Tree Scientists claim billions more could follow as early as this autumn."

Maybe if you instructed ChatGPT to use this premise to write a satirical article expressing a certain point of view it would?

I searched "site:theonion.com leaf falls tree" and found this which is pretty good:

https://www.theonion.com/leaf-hunting-season-begins-18195730...