While C# is a particularly egregious case, I think all reasonably long-lived, popular languages suffer from this problem. Go is being very intentional about not falling in this trap, but JavaScript, Python, Java.. modern/idiomatic code in all of these languages looks very different from the code you'd write using them 15 years ago.

At my workplace, we use the .editorconfig and static analysis heavily to push us towards a consistent C# feature-set and style. This plays the same role that pyupgrade would in python, for instance.