This is a violation of UN regulation 155/156 where the vendor must provide free fixes and updates in case of safety or cybersecurity violations.

I'm mentioning this specifically because the CAN bus is involved, which is mandatory to be safety conform and has to be ASIL-C/D conform. If you cannot guarantee that, you will lose the license.

Without conformance to UN Regulation 155/156, the car manufacturer might lose its license for the underlying car platform (not only the downstreamed models), meaning refunding/damages need to be paid for all buyers of cars of that platform.

So chances are this can be fought in court, and Hyundai probably has to offer free replacement of that defective part.