A taint is applied to a node that indicates only specific pods can be scheduled on them. A toleration is then applied to a pod that allows them to tolerate a node's taint. The Kubernetes scheduler can use taints and tolerations to restrict what workloads can run on nodes.
You can find if the node has applied with taint by running the command below:
kubectl describe node <node name> | grep Taints
However, You can't change node taints through the CLI after the node pool is created.:
Here is a thread discussing on this: https://github.com/Azure/AKS/issues/1402
You may plan for a fresh new nodepool in this situation
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