On US healthcare bills there is:
Billed Amount - what the provider/health system tags as the “billed amount” Allowed Amount - what the insurer sets as the actual total $ allowed to change hands for the visit Patient Responsibility - the portion the patient is responsible for.
The Billed Amount is supposed to exceed the Allowed Amount by 2.5-5x typically so that the Allowed Amount the insurer/provider has negotiated “saves” money thanks to Insurance ostensibly in how the bill is displayed.
Put differently, your provider/health system is supposed to per the billing contract put in an inflated value well in excess of expected payment so your insurance company can reduce it so you can “save money” superficially on your bill. It is as smoke and mirrors as it sounds. Sounds like your provider / HS forgot healthcare billing 101 in this case.
The Billed - Allowed Amount value is also usually called Contractual Adjustment