[stonepresto]

The part of the prompt that suggests its the 15th of December is a GET param, which just means wherever this link was retrieved from is where that date is coming from.

The PDF could have been authored at any time.

Looks like the created date embedded in the metadata is as follows:

2023-12-18T21:21:19.000Z

Created with MS Word. But even that isn't definitive.