Q: Cannot spoof MAC Address on Macbook Pro 2019 13.3 on Big Sur Beta 4 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?
I had same issue, your solution actually works
sudo ifconfig en0 ether yourspoofedmacaddress

What you have to do is hit up arrow in terminal and keep reentering it rapidly about 3 times and then it changes.  I needed to do this to Login to a captive wifi and my IOT devices can't do that so have to spoof from my Mac.