It changes the dual-stack API wrt Service from a single ipFamily field to 3
  fields: ipFamilyPolicy (SingleStack, PreferDualStack, RequireDualStack),
  ipFamilies (a list of families assigned), and clusterIPs (inclusive of
  clusterIP).  Most users do not need to set anything at all, defaulting will
  handle it for them.  Services are single-stack unless the user asks for

- On single-stack configured (IPv4 or IPv6, but not both) clusters, Services which are both headless (no clusterIP) and selectorless (empty or undefined selector) will report `ipFamilyPolicy RequireDualStack` and will have entries in `ipFamilies[]` for both IPv4 and IPv6.  This is a change from alpha, but does not have any impact on the manually-specified Endpoints and EndpointSlices for the Service. ([#99555](https://github.com/kubernetes/kubernetes/pull/99555), [@thockin](https://github.com/thockin))...

- The `Service.spec.ipFamilyPolicy` field is now *required* in order to create or update a Service as dual-stack.  This is a breaking change from the beta behavior.  Previously the server would try to infer the value of that field from either `ipFamilies` or `clusterIPs`, but that caused ambiguity on updates.  Users who want a dual-stack Service MUST specify `ipFamilyPolicy` as either "PreferDualStack" or "RequireDualStack". ([#96684](https://github.com/kubernetes/kubernetes/pull/96684), [@thoc...