I must admit I never looked at that ecosystem. Does it just happen to have been quite stable or is it a serious design decision they made and are sticking to?
From a quick search I do not get the impression that .NET has been deprecating parts of the API, including Core APIs, in the past, e.g.:
.NET was pretty stable. I remember porting old .NET Framework 4.x MVC web app to .NET Core 2, and then to .NET 5. Both times it took less than an hour to port. Old directory structure and APIs still work even if they are not the new hot way to do things. Microsoft is known for backward compatibility.
