Pylance started as open source and moved to a closed source model. Relevant discussion is at [0].
Then, they closed the .NET ecosystem [1]. This is a bit more complex and convoluted. Closed source debuggers, changing plug-in licenses, removing nice features from open source .NET runtime, etc.
Then, they closed the .NET ecosystem [1]. This is a bit more complex and convoluted. Closed source debuggers, changing plug-in licenses, removing nice features from open source .NET runtime, etc.
So, classic Microsoft.
[0]: https://news.ycombinator.com/item?id=31763107
[1]: https://isdotnetopen.com/