If you want to use Visual Studio Code the 'DevKit' extension which provides essential features (language server) is proprietary and requires a Visual Studio licence regardless of platform.
Also I find since C# is an 'enterprise' language developers take the p--s in what they want to charge for, as enterprise will pay as a 'cost of doing business'. Recently FluentAssertions, a freakin test assertion library decided they wanted to charge for newer versions. You don't get that in other languages like Python/Ruby etc.
The language server is part of the SDK itself. The language server integration, debugger and all the features that make VS Code a good tool to write C# in are a part of base C# extension which is MIT-licensed and has no commercial restrictions whatsoever.
The only "wart" is that "vsdbg" - debugger it ships with is closed-source because it is essentially the same debugger as in Visual Studio but extracted into a standalone cross-platform component. There is an open alternative "NetCoreDbg" used by the extension fork for VSCodium (and various DAP bridges to Neovim, Emacs, etc.).
Also I find since C# is an 'enterprise' language developers take the p--s in what they want to charge for, as enterprise will pay as a 'cost of doing business'. Recently FluentAssertions, a freakin test assertion library decided they wanted to charge for newer versions. You don't get that in other languages like Python/Ruby etc.
https://youtu.be/ZFc6jcaM6Ms
Don't get me wrong, C# is my dayjob and I love the language but for personal projects where I don't have the money I'd be hesitant to touch it.