Do worker nodes in a multi-master setup talk to the apiserver on the master nodes via the load-balancer? It seems like the cluster is aware of the active apiserver endpoints via the endpoint reconciler, so I would think the logical and HA way is for the worker nodes to talk to the active endpoints it knows of. But according to the official documentation/diagram (https://kubernetes.io/docs/admin/high-availability/building/), it shows that the worker nodes goes through the load-balancer. Doesn't this mean that if for whatever reason the load-balancer becomes unavailable, your worker nodes will also malfunction?
When your kubelet starts, it needs to connect to the apiserver. The location of the apiserver is provided as a configuration option and in most cases will be a non-changing domain name pointing to a loadbalancer. You can not rely on ClusterIP based service for kubernetes main components like kubelet or kube-proxy as you would essentially be running your self into a chicken-and-egg situation / introducing additional dependencies.
Any reasonable environment should have a dependable loadbalancer, and it it is down, odds are that quite a lot of other things is down (also keep in mind that in many cases kubernetes will survive temporary inaccessibility of control plane)