I tried this but I didn't work. When I googled it, I found out that Apple has disabled this in BigSur. Here is the link to it: https://developer.apple.com/forums/thread/106768

It looks like iproute2mac[0] will let you change your MAC address. It can even set a random one.

Could you try if it works on your Apple device?

[0]: https://github.com/brona/iproute2mac