If you don’t supply a document icon for a file type you support, macOS 11 creates one for you by compositing your app icon and the file’s extension onto the canvas.
Although I’m not sure what does the last part of the quotation (“onto the canvas”) mean, after removing the icon from the filetype-set of an app of mine (but keeping all the old data), I saved a doc. But the doc showed the same icon as before.
Then I created a new filetype-set with a new name and no icon, and I increased the non release version number. The saved file showed a black icon.
So I’d like to know if there are declares available to achieve this goal.
Or am I missing something obvious? It wouldn’t be the first time…