I upgraded the BIOS to 2.22.2 first with a patch to the HostFirmwareComponents CR that added the bios url:
    '"spec": {
        "updates": [
            {
                "component": "bios",
                "url": "http://hv14.telco5gran.eng.rdu2.redhat.com:8888/firmware/r740/BIOS_F8GPH_WN64_2.22.2.EXE"
            }
        ]
    }'

After that completed, I added a bmc url to the spec.updates list:
    '"spec": {
        "updates": [
            {
                "component": "bios",
                "url": "http://hv14.telco5gran.eng.rdu2.redhat.com:8888/firmware/r740/BIOS_F8GPH_WN64_2.22.2.EXE"
            },
            {
                "component": "bmc",
                "url": "http://hv14.telco5gran.eng.rdu2.redhat.com:8888/firmware/r740/iDRAC-with-Lifecycle-Controller_Firmware_RVDDR_WN64_7.00.00.181_A00.EXE"
            }
        ]
    }'

Because the spec.updates list is taken as a whole, the addition of the bmc url triggered an upgrade of both. In the case of the bios image, it ends up performing an upgrade unnecessarily.

    

OCP: 4.18.5
MCE: 2.7.2
    

    1.
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    3.
    

The bios firmware undergoes a no-delta upgrade, re-applying the previously applied image.
    

Since the bios entry in the status.updates list has the same url value as the spec.updates list entry, a possible optimization would be to skip the bios firmware upgrade and just do the bmc upgrade.