Istio Ingress : Increase Header size

Hello,

Istio Version : 1.7

I am trying to update max_request_headers_kb to 80 using below envoy filter:
Even after applying one of below EnvoyFilter I am getting “431Request Header Fields Too Large” on header size beyond 30 kb.

I know the document from envoy says default limit is 60 kb but in code its hardcoded to 29 and max limit to 94.

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
name: custom
namespace: istio-system
spec:
workloadSelector:
labels:
istio: ingressgateway
configPatches:

  • applyTo: NETWORK_FILTER # http connection manager is a filter in Envoy
    match:
    context: GATEWAY
    listener:
    filterChain:
    filter:
    name: “envoy.http_connection_manager”
    patch:
    operation: MERGE
    value:
    max_request_headers_kb: 80

OR

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
name: custom
namespace: istio-system
spec:
configPatches:

None worked.

Can someone suggest what am I doing wrong?