Surprise! Everything everyone types into Microsoft software is recorded and uploaded!
I think you need to actually get the new data from Github and finetune the model. Maybe it's done very frequently, but unlikely.
I'd bet good money, they aren't ingesting, retraining, and pushing production copilot models on a subdaily basis.
i think that's kind of the point behind gpt style models, updates are cheap ... not only in terms of source material but also feedback on which suggestions are accepted.