You Can Send Invisible Messages With Subtle Font Tweaks May 20, 2018 https://www.wired.com/story/fontcode-invisible-messages-steganography/
That's nice. But I'm guessing that there are a limited number (one?) of encoding schemes. And the bit about watermarking is disturbing. But converting to plain text would prevent that. Except stylometry, of course.
Ahhh. More Dick Tracy secret messaging apparatus. Seems something similar was explored way back on Windows 98 using fonts as a cover but I suppose about anything can be dug back up and modified to fit the current windows format as-is. Interesting concept but then there are already too many methods to count with which conceal digital writings here, there, and everywhere. It is Windows after all. The best copy machine ever dreamed up.
Not so stego now that this article is published. Even if encrypted, it will be easy to identify the existence of hidden data. For example, take all lower case "g" characters and look at how they vary across the document.
I would bet that China and Russia (to name just 2) have people trained to spot this method. I suspect that a human could learn to spot it but they could also make an app to pick it out of a photo or scan.