Breaking change. It’s gone from plain text to a markdown formatted text (possibly). There’s changing an interface (obviously a breaking change) and then there’s changing the semantics of a function. I just dealt with a breaking change where a string error value changed for an account registration api call. Previously it returned EMAIL_IN_USE and now it returns EMAIL_TAKEN. Same data type but it broke the client code. Changing values or formats is a breaking change. In your case the documentation says don’t rely on this function for anything but once the output is in the wild any monkey can start using it for anything and it can’t be certain that some code documentation will be consulted before deciding to depend on it.