I've been having problems with obtaining a fixed IP address from my home router, as MacOS would randomly change my MAC address (what Apple calls the Wi-Fi address) even when the new rotate address option was turned off.
It would *usually* give the same MAC add news! ress but occasionally invent a new one, sometimes even after just shutting the lid. This could cause my router to think "oooo, shiny new computer! Better give this one a different IP address".
I was just checking, and this hasn't happened again on this new beta. And there's a new option in settings too.
* Edit: it has happened again, when opening the lid after leaving it closed for an hour or so.
I've not yet worked out the difference between "off" and"fixed" but my guess is that "fixed" means I'll always get the same MAC address when connecting to this network (whee!) whereas "off" means it may create a new one, but then won't change it while you remain connected.
It's still a slightly annoying feature to me, as I used to have my 5 GHz and 2.4GHz networks combined, and I can no longer do that as there's no way to present the same MAC address to both networks, even though they share the same SSID.
Edit: This is big news! Well, big news to me
I've just changed the setting from the new "Fixed" to "Off" and I have a privacy warning and it is giving my original/correct/actual/real MAC address to my network.
I changed the setting to "Off" for my 2.4GHz network as well as the 5GHz one and it is going to give the same MAC address to both. This is great!
So ... "Rotate" means the MAC address will change every now and again when you're connected to the network. "Fixed" means it won't change while you're connected, but may change when you disconnect and re-connect a while later, and "Off" means it'll never change and it will be your actual hardware MAC address.