In Service Mesh 2.6 which uses  envoy version 1.20.8 there was a change that made is so headless services need the port type defined in the name.

https://istio.io/latest/docs/ops/common-problems/network-issues/#503-error-while-accessing-headless-services

Was wondering if we could amend the 2.6 docs so this was mentioned as this could break a customers headless service if they update from 2.5 which is based on 1.18.7