Here https://source.android.com/devices/tech/connect/wifi-mac-randomization is the MAC Randomization described and stated
Note: Randomized MAC addresses are generated per SSID and are
persistent.
I can confirm, deleting the SSID, rebooting and connecting again there is the same random MAC as before. However if you reset the device to factory defaults and connecting to the same SSID, the device connects with another random MAC address. So how can you trigger this behaviour without doing a factory reset?