Most IPv6 packets are encapsulated in Ethernet frames which use MAC addresses. What may change is the vendor specific MAC address could be replaced with a MAC address generated by a cryptographic hash to preserve privacy.

Privacy from what? MAC addresses are not used on the internet, only on the local network

Not all networks are private. Also, many IPv6 addresses contain the MAC address which would effectively deanonymize you over the internet.

So instead of not using the MAC address in the IPv6 (which any reasonably modern OS does because this problem is old, well known and trivially solved) you get rid of MAC addresses altogether? Just so you can have some illusion of privacy while sending your traffic through a supposedly compromised network?

This is paranoia about all the wrong things, focusing on irrelevant details and ignoring what’s important.

I don't believe I suggested getting rid of the MAC address altogether. Ethernet isn't going away anytime soon.

The suggestion is simply this: Don't embed your MAC address into your IPv6 address because it's a unique identifier that can deanonymize you even if you shift networks.