What would you like to be added:
I am using traefik to configure a middlewere once in the infra-ns. I would like this middlewere to be available in other namespaces for HTTPRouteFilter to use
https://gateway-api.sigs.k8s.io/reference/spec/#httproutefilter
According to spec extensionRef is LocalObjectReference which is bound to the same namespace

Why this is needed:
https://gateway-api.sigs.k8s.io/guides/multiple-ns/?h=cros#cross-namespace-routing
Since "Gateway API has core support for cross Namespace routing. This is useful when more than one user or team is sharing the underlying networking infrastructure, yet control and configuration must be segmented to minimize access and fault domains."
It just make since to have some middleweres at infra level.