I mean if your code is already hosted on Github, your builds done by github actions, and/or issues managed by github issues, it's not like giving MS that same code back is going to increase "liability" at all.
Setting aside the possibility that not all code is actually hosted on GitHub; If your code’s hosted in a GitHub account owned by your company, under terms vetted by legal… but then you sign up personally for copilot and in that capacity you upload the same code to GitHub under terms and conditions your corporate legal team have no visibility into? You might have a problem.