> It has been some years since I read about the original document leak, but as I recall, she shared documents from her workplace that either had printer steganography ID codes embedded into them (images in a raster scan of a paper document), or some form of digital stego IDs in electronic documents.

All modern printers have this steganography feature.

"In October 2004, consumers first heard of the hidden feature, when it was used by Dutch authorities to track down counterfeiters who had used a Canon color laser printer." [1]

This is written in "PC World" in 2004 by journalist Wilbert de Vries. He now works for Tweakers, back then he worked for Webwereld. 2004 was mid-end heydays of Webwereld. I'm quite sure I read about this technology on Webwereld back then.

Later on, this got covered on CCC as well, not sure which years.

My point / opinion? The Intercept could have known (see above), and, given he nature of their content ([2]), should/ought to have known.

[1] https://en.wikipedia.org/wiki/Machine_Identification_Code

[2] The fact they had Greenwald/Poitras on board says enough (they were key figures in the Snowden leaks). You can look at their content from the era 2017 if in doubt.