Reset of "BootSourceOverrideEnabled" to "Disabled"

It really depends on your system design. Some system vendors will have UEFI tell the BMC that it consumed the request and performed the one-time boot, and in other designs the BMC sets it automatically when UEFI reads it out of the BMC. UEFI may not even use Redfish to collect this information; this is also another design detail by the implementer.

However, the user is unaware of this aspect. Redfish as a standard describes what is presented to the user and what behaviors to expect; it does not mandate how this works internal to the system. From their perspective, as long as the settings goes back to Disabled after the one-time boot, then it meets the desired functional behavior.