Tested and verified in 4.8.0-0.nightly-2021-04-19-071934

[weliang@weliang Config]$ oc get crd | grep egress
egressnetworkpolicies.network.openshift.io                        2021-04-19T13:33:10Z
egressrouters.network.operator.openshift.io                       2021-04-19T13:24:52Z
[weliang@weliang Config]$ cat test2.yaml 
apiVersion: network.operator.openshift.io/v1
kind: EgressRouter
metadata:
  name: egress-router-test
spec:
  addresses: [
    {
      ip: "192.168.3.10",
      gateway: "192.168.3.1",
    },
  ]
  mode: Redirect
  redirect: {
    redirectRules: [
      {
        destinationIP: "203.0.113.25",
        port: 65,
        protocol: TCP,
        targetPort: 75
      },
      {
        destinationIP: "203.0.113.26",
        port: 65535,
        protocol: SCTP,
      },
      {
        destinationIP: "203.0.113.27",
        port: 65534,
        protocol: UDP,
      },
    ],
    fallbackIP: "203.0.113.28"
  }
[weliang@weliang Config]$ oc create -f test2.yaml 
egressrouter.network.operator.openshift.io/egress-router-test created

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Moderate: OpenShift Container Platform 4.8.2 bug fix and security update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2021:2438