Would you mind sharing what ecosystems?
I have been working on 2 mil. LOC C# written by more than 100 developers over 15 years and it is really good experience.
>but they have revamped C# libs/platform so many times I have lost count.
What exactly do you mean? There was big migration towards .NET Core but full .NET will be supported forever. They even listened customers regarding WCF and helped a lot with CoreWCF.
Oh and on top every major dependency being a copy of the java’s version, and only the microsoft version will be remotely maintained. But please do correct me if my flamewary knowledge on the topic is not accurate.