Well, have you actually read the license for the auto complete function?
Example,
https://marketplace.visualstudio.com/items/VisualStudioExptT...
Example,
https://marketplace.visualstudio.com/items/VisualStudioExptT...
Pretty sure it depends on the license the open source project uses. I dont think it's too troublesome if the autocomplete was truly only taken from open source projects, but it wouldn't surprise me if most closed source projects are also weighted into these models...