[ndiddy]

The harm is that third-party developers aren't allowed to publish extensions that use "proposed APIs", but Copilot doesn't have to follow these rules because Microsoft both develops the extension and runs the Extension Marketplace website. Microsoft is therefore able to add functionality to their extension that third-party developers can only add by forking VS Code. VS Code forks lose access to the Extension Marketplace, and many Microsoft-published extensions (such as Pylance and LiveShare) will only run on official Microsoft builds of VS Code, not forks.