What happened: No error or warning message when service modified only with partially success.

What you expected to happen: Error or warning message when the service is not fully successful configured by yaml file.

How to reproduce it (as minimally and precisely as possible):
Service creation by this yaml is ok:

apiVersion: v1
kind: Service
metadata:
  labels:
    app: exampledeployment
  name: example-svc
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    app: exampledeployment

Modifying with this yaml reports success configuration, but it is not true, because port dnsudp is missing.

apiVersion: v1
kind: Service
metadata:
  labels:
    app: exampledeployment
  name: example-svc
spec:
  ports:
  - name: dnstcp
    port: 53
    protocol: TCP
    targetPort: 53
  - name: dnsudp
    port: 53
    protocol: UDP
    targetPort: 53
  selector:
    app: exampledeployment

$ kubectl apply -f tcp_udp_ports.yaml
service/example-svc configured

$ kubectl get svc example-svc -o yaml

apiVersion: v1
kind: Service
...
  ports:
  - name: dnstcp
    port: 53
    protocol: TCP
    targetPort: 53
  selector:
    app: exampledeployment
  sessionAffinity: None
  type: ClusterIP
status:
  loadBalancer: {}

As outputs show: the dnsudp udp/53 was not configured into the service and no error or warning message about it.

Anything else we need to know?:
The service can be created from scratch with kubectl create and both ports are configured:

$ kubectl create -f tcp_udp_ports.yaml
service/example-svc created

$ kubectl get svc example-svc -o yaml

apiVersion: v1
kind: Service
...
  ports:
  - name: dnstcp
    port: 53
    protocol: TCP
    targetPort: 53
  - name: dnsudp
    port: 53
    protocol: UDP
    targetPort: 53
  selector:
    app: exampledeployment
  sessionAffinity: None
  type: ClusterIP
status:
  loadBalancer: {}

If type of service is changed to LoadBalancer from ClusterIP, the creation will be failed, but the modification of existing service is same as above.
$ kubectl apply -f tcp_udp_ports.yaml
The Service "example-svc" is invalid: spec.ports: Invalid value: []core.ServicePort{core.ServicePort{Name:"dnstcp", Protocol:"TCP", AppProtocol:(*string)(nil), Port:53, TargetPort:intstr.IntOrString{Type:0, IntVal:53, StrVal:""}, NodePort:0}, core.ServicePort{Name:"dnsudp", Protocol:"UDP", AppProtocol:(*string)(nil), Port:53, TargetPort:intstr.IntOrString{Type:0, IntVal:53, StrVal:""}, NodePort:0}}: cannot create an external load balancer with mix protocols

Environments:

• Kubernetes version (use kubectl version): v1.19.3, v1.20.1
• Cloud provider or hardware configuration: (no cloud provider) VMs on vmware and QEMU/KVM
• OS (e.g: cat /etc/os-release): Ubuntu 20.04 LTS (Focal Fossa), Debian/GNU Linux 10 (buster)
• Kernel (e.g. uname -a): 4.19.0-12-amd64, 5.4.0-33-generic
• Install tools: kubeadm