::ffff:0:0/96 is for representing v4 addresses in v6 APIs. If you tell the kernel you want to send a packet to ::ffff:1.2.3.4, you're actually telling it you want to send a (v4!) packet to 1.2.3.4, you're just doing it using an AF_INET6 socket rather than an AF_INET one.
Since packets aren't APIs, you should never see ::ffff:0:0/96 in packets on the wire. A v6-only host can't use this prefix to send v4 packets to v4 hosts.
(What would the source address of those packets even be?)
Since packets aren't APIs, you should never see ::ffff:0:0/96 in packets on the wire. A v6-only host can't use this prefix to send v4 packets to v4 hosts.
(What would the source address of those packets even be?)