Donna could already "Export" placeholders by highlighting them in the document. This ensured that if you sent the document to a colleague the highlights would still be visible even with Donna closed.
Now you can select what kinds of placeholders you would like to include. You can even select what color each kind of Placeholder type should have. Sadly the colors are still limited to the palette provided by Microsoft Word. But I guess retro colors never go out of style? 🤷♀️