Someone asked by email:
Where are the Ethernet MAC addresses stored in the ADRV9361-Z7035?
In the production test for the ADRV9361-Z7035:
it should write a U-Boot environment into the on-board SPI Flash.
That is managed here:
There are some notes on how to set this at (which doesn't go into the details of where things are set).
but it should let you find things with the default image.