I usually change my MAC Address frequently and it worked perfectly on Catalina, however when I transitioned to Big Sur it didn't seem to work correctly, at least for Beta 4. I would run the command
sudo ifconfig en0 ether yourspoofedmacaddress
where I confirmed that en0 is my wireless device.
I would expect that after running
ifconfig the en0 interface ether would display the spoofed mac address, and it does, but as soon as it connects to any wifi connection, the en0 interface reverts right back to the original MAC address.
This also happens after I try to spoof any interface MAC address including en1, en2, and en3. These interfaces aren't used at all, but once en0 receives any type of network connection, all of the spoofing reverts.
Any ideas as to why it might not work anymore in Big Sur or any workarounds for that matter?