OK I can confirm that this behavior change has been introduced by commit 6d36464065601f7. Indeed due to this specific change [1], the device name is now used for generating a predictable unique MAC address when it's not been defined through the ID_NET_NAME_* variables. Previously, udev failed to get a predictable unique name (because ID_NET_NAME_* were not defined) and left the MAC address unchanged. Apparently in this case the kernel chooses the MAC address of the enslaved interface. [1] https://github.com/systemd/systemd/commit/6d36464065601f79a352367cf099be8907d8f9aa#diff-40d09511b873893493866eda6c777e92L51