Error updating load balancer with new hosts map[..]: nsg "..." not found

Description of problem:
After upgrading the cluster from 4.8 to 4.9 (4.9.51) below warnings are observed continuously in the cluster:

Error updating load balancer with new hosts map[..]: nsg ".." not found

Version-Release number of selected component (if applicable):4.9.51

How reproducible:

Steps to Reproduce:

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Actual results:
Warning messages always display below:
Error updating load balancer with new hosts map[..]: nsg "<nsg_name>" not found
Whereas "nsg" mentioned in the logs has never existed.

Expected results:
Warning message for nsg not found should not exist.

Additional info:

• Infrastructure details:
  Platform: Azure
  Install Type: IPI
  cloudName: AzurePublicCloud
  Network Type: OpenShiftSDN
  Cluster Version: 4.9.51