Comment by magicalhippo

Software support is a big one. I ran pfSense. It did not support changing IPv6 prefixes. It still barely does. So something as simple has having reliable IPv6 connectivity and firewall rules with pfSense was impossible just a few years ago for me.

Android doesn't support DHCPv6 so I can't tell it my preferred NTP server, and Android silently ignores your local DNS server if it is advertised with a IPv4 address and the Android device got a IPv6 address.

Without DHCPv6 then dynamic DNS is required for all servers. Even a 56 bit prefix is too much to remember, especially when it changes every week. So then you need to install and configure a dynamic DNS client on all servers in your network.