Yes, most of them.

C# for instance isn't such a "small language", it has grown, but code from older versions, that does not use the newer features will almost always compile and work as before.

breaking changes are for corner cases, e.g. https://github.com/dotnet/roslyn/blob/main/docs/compilers/CS...

The thing is that "most of them" seems incongruous with a demand for "absolute non-negotiable" backwards compatibility. If not for that particular wording I probably wouldn't have said anything.