I opened VT-d in the BIOS and deleted the memory area of the DMAR table according to your guide. After entering the system, I saw that "AppleVTD" has been successfully loaded.
Since upgrading Big Sur, the network card (BCM57762) of my Thunderbolt 3 docking station has been unavailable. After turning on "AppleVTD", it successfully works normally and supports AVB.
Ethernet and WiFi are still normal, but unfortunately the sound card doesn’t work anymore. Turn off vt-d in the BIOS and it works normally."AppleHDAController.kext" shows that it has been loaded, but "AppleHDA.kext" has not been loaded, and the layout-id has been successfully injected in ioreg.