I am not sure your software has been assimilated into a proprietary blob. Rather, it's been sliced into its constituent parts and those parts have been tagged by the proprietary blob.

Your code isn't being run by Copilot, as such; it's been categorized in a way that allows partial retrieval without the license or attribution. This might seem like a distinction without a difference, but it's kind for a ship-of-theseus problem; probably nobody is running any of your programs in their entirety, but it's very possible that bits of your code have found your way into other people's programs. How do you distinguish between contributions that are uniquely yours, and those which are just helper functions or cobbled together from other example code, eg in documentation or from a book or Q&A website?