I think you need to distinct LCI *) from IPv6.
In IPv6 the problem is less interesting. It is addressed.
In IPv6 you are well advised to set ip6-privacy to value 2 NOT to reveal information that can lead back to calculating your MAC.
ipv6.ip6-privacy: 2 (enabled, prefer temporary IP)
quick check what you really do reveal: http://ip.bieringer.de/
details about settings:
there is a set of tools available. for CLI use I prefer nmcli.
Examples to identify and set the status:
nmcli con show [assume our connection is named ethernetvenus00 here]
sudo nmcli connection modify “$con” ipv6.ip6-privacy 2
sudo nmcli connection modify “$con” ipv6.addr-gen-mode eui64
sudo nmcli connection modify “$con” ethernet.cloned-mac-address permanent
sudo nmcli connection modify “$con” wifi.cloned-mac-address permanent
more pretty to watch here:
*) Last Century Internet = IPv4