“Microsoft’s vscode source code is open source (MIT-licensed), but the product available for download (Visual Studio Code) is licensed under this not-FLOSS license and contains telemetry/tracking.”
Microsoft gets the open source halo for the repo and ships something else. The binary you download carries a proprietary license and phones home. A Microsoft maintainer admits the difference is one customized product.json file. VSCodium is just build scripts that compile the same code without it. That a community has to do this for you says everything about what Microsoft wanted from “open source.”