All my Linux servers create a EUI-64 IPv6 address.  You can tell them by the FF:FE.   It uses the first 64-bit of the delegated prefix and breaks the 12 character MAC Address in half inserting FF:FE in the middle.  AT&T gave me a prefix delegation of 2600:1702:980:25e0 to start with.   Let’s say my MAC address is 00-D8-61-F4-A9-23

Server with this NIC gets the address 2600:1702:980:25e0:00d8:61FF:FEf4:a923