This provision allows working seniors who are eligible for Medicare Part A, but enrolled in an HDHP, to continue contributing to an HSA. The current guardrails that apply to individuals that are under 65 and are contributing to HSAs would continue to apply to this population, including a penalty on non-qualified medical expenses purchases. […] This provision allows individuals with HDHPs to also enroll in DPC arrangements (and maintain their HSA) and allows HSA funds to be used to pay for DPC services.
Source: wiktionary