Node had taints that the pod didn't tolerate error when deploying to Kubernetes cluster

You can run below command to remove the taint from master node and then you should be able to deploy your pod on that node

kubectl taint nodes  mildevkub020 node-role.kubernetes.io/master-
kubectl taint nodes  mildevkub040 node-role.kubernetes.io/master-

Now regarding why its showing as master node check the command you ran to join the node with kubeadm. There are separate commands for master and worker node joining.

You can also get this "taint" type of message when your docker environment doesn't have enough resources allocated.

For example, in Docker Desktop for Mac, allocate more memory/cpu/swap in preferences, and it may solve your problem.

This can also happen if kubernetes auto scaling doesn't have enough nodes to launch a new pod, which you will may see as "Insufficient CPU" on describe.