[neonsunset]

C# language server, being Roslyn Language Server, is plugin agnostic, it's MIT licensed and is essentially a part of the compiler: https://github.com/dotnet/roslyn/tree/main/src/LanguageServe....

Did you mean to say a debugger? That one has an open alternative (NetCoreDbg) alongside a C# extension fork which uses it (it's also what VS Codium would install). It's also what you'd use via DAP with Neovim, Emacs, etc.

[zamalek]

Nope, OmniSharp - which uses that AFAIK, is what I'm referring to. Something being open source doesn't automatically make it good.

[neonsunset]

Omnisharp is what the base C# extension used previously. It has been replaced by Roslyn LS (although can be switched to back still). You are talking about something you have no up-to-date knowledge of.