Copilot sends chunks of your code to the server for every suggestion (whether or not you accept it). That's the only way it could possibly work, since the model is running on a remote server.
When I looked into this a little bit, I found Copilot for Business states they do not record any of the info you send them. Though obviously you are still sending out code to a third party. I could not find any info about their policies for “normal” Copilot which I assume means they are recording all the code sent to it and using our code to further train the model.
Still hard to trust. Many companies save info for training/qa purposes and hide details in obscure language. Voice assistants for example. Didn't Roomba get in trouble recently regarding photos uploaded and then shared with contractors for qa that ultimately shared the embarrasing photos more publicly.
https://thakkarparth007.github.io/copilot-explorer/posts/cop...