Vscode does not use react specifically for the licensing reason. I don’t know if they do now but when I was at MS this was the case. I know many teams at MS who evaluated react and lawyers strictly advised to stay away from it. I hear things have changed a bit, but you’ll never see Office and Windows use it.
That’s not “Office uses React”, it’s a “collection of robust components designed to make it quick and simple for you to create web experiences using the Office Design Language.”
Very limited “use”; mostly just enabling external developers to interface using React to their existing tools (that are not using React). If the Armageddon should come, and Microsoft is to enter a legal patent dispute/battle, stopping this React “use” is a no-op for Microsoft.
Microsoft builds Skype on React Native. They use React in production on several websites including outlook.com. They are using it internally and not just for external devs.
You'd be actually surprised how many teams inside Microsoft wrote their own smaller versions of OS libraries. It happened a lot less after Nadella era, but Ballmer era had a "we can't use anything not built here"
you mean vs code, which is a separate product from "visual studio"