Pruning the response would help validate your response schema is correct and that is delivering what was promised.

But you're right, if you have version skew and the client is expecting something else then it's not much help.

You could do it client-side so that if the server adds an optional field the client would immediately prune it off. If it removes a field, it could fill it with a default. At a certain point too much skew will still break something, but that's probably what you want anyway.