After upgrading the cluster to 4.14.16 from 4.12.26 Cu got disk pressure in infranode3 so to resolve that Cu deleted the node and so machine-set automatically created a new machine which came to ready state and ran some important pods but Cu can't schedule more pods to it due to uninitialized taint.

--> The taint was not removed unless removed manually. 
--> According to the Cu the below shown labels were not added to the new node:
labels:
  - failure-domain.beta.kubernetes.io/zone: westeurope-3
  - node.kubernetes.io/instance-type: Standard_D16s_v3
  - failure-domain.beta.kubernetes.io/region: westeurope
  - beta.kubernetes.io/instance-type: Standard_D16s_v3
  - topology.kubernetes.io/region: westeurope
--> Also after analyzing more, Cu got to know that the new nodes do not get any public ip which means that the new virtual machine was not added to the gateway backend pool.
--> No changes were made in the machine-set after upgrading the cluster.
--> Cu has enough range of ips for his cluster.
--> The cluster is not configured with accelerated networking so the bug faced due to upgrade is not possible.
--> The newly added node is in "Ready" state but taint is still present.

    NA

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    Should be upgraded to 4.14.16

 When Cu added the VM to the default backend pool manually using "az" command and removed the taint manually, everything worked fine.