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Please check if there are any Azure policies or Key Vault access policies configured at Management group or subscription level that might be conflicting with your configuration. To resolve, Make sure that there are no policies in place that automatically disable public access.
Please check below Image for policy which needs to be removed if in place
Ref for MS doc --> https://learn.microsoft.com/en-us/azure/key-vault/policy-reference
Kindly accept answer if it helps ,