We don't currently run the k8s conformance tests on dual-stack clusters. I ran it manually and got the following error:

[FAIL] [sig-network] [Feature:IPv6DualStack] Granular Checks: Services Secondary IP Family [LinuxOnly] [It] should function for service endpoints using hostNetwork

To run the tests manually, download e2e.test, create a dual-stack kind cluster with kube-proxy replacement, and run

$ ./e2e.test-1.26 --provider=local --kubeconfig kubeconfig.conf --ginkgo.focus "\[sig-network\].+DualStack.+should function for service endpoints using hostNetwork" -delete-namespace-on-failure=false               

The test that fails attempts to send a large (~2000 byte) udp packet back and forth between a client and a host-network server. This succeeds for ipv4 but does not for ipv6. I also tested directly via pod IPs and it also fails for ipv6 but works for ipv4.