"[A] bipartisan group of senators [has] released new legislation to address surprise medical bills ... by prohibiting balance billing for categories of services where surprise bills commonly arise and prescribing an initial payment from insurers tied to median in-network rates, with the option for providers or insurers to initiate an arbitration process to challenge this rate. By tying automatic payment to the insurer's median in-network rate ... the [STOP Surprise Medical Bills Act] could reduce health care costs as well, although the existence of arbitration as a backstop makes that uncertain."