There was one huge breaking change, that was the move from the Windows-only .NET Framework to the cross-platform .NET Core. I assume that is the one the parent

There was one huge breaking change, that was the move from the Windows-only .NET Framework to the cross-platform .NET Core. I assume that is the one the parent is talking about. The major releases of modern .NET are relatively painless now, there aren't that many breaking changes. This is pretty much the same as many other languages, and kinda unavoidable unless you go for an ecosystem that aims for very long term stability and is essentially frozen. The early .NET Core releases had some annoying breaking changes, but it's very different today.