That was my whole point. There are not 2^128 ipv6 addresses for Individual use but there are 2^64 /64 networks.

If you rent a vps with a ipv6 “address” you will see that you are given a /64 network.

There is no effort to “fix” the bottom 64 bits because it’s not needed. There are enough /56 networks to for the next 500 years and 99% of people can do everything they need with an isp provided /56. IPv4 has survived with 48 bit nat for this long so 64 bit is even more buffer space