random MAC address at every raspberryPI boot?

create script „/etc/network/if-up.d/wlan0-setmac“ with content to set a static MAC:

#!/bin/sh

if [ "$IFACE" = wlan0 ]; then
    # use your own uniq MAC address here!
    ifconfig wlan0 hw ether B8:27:8F:A2:45:9E
fi