H8000 is now a very old product. It is unlikely that there will be any new drivers in the future.
Anyone who needs its FireWire capability should NOT upgrade to Big Sur, which is not supported.
We are aware that there are FireWire adaptors, but have not had success with them with H8000.
We would recommend that any one who needs to connect H8000 to a Big Sur system obtain an AES interface and use this instead of FireWire.