Azure policy for naming conventions for subnets to start with "snet", but allow subnet names like "AzureBastionSubnet", "AzureFirewallSubnet", etc

I'm creating an Azure policy that enforces a naming convention for my subnets. The subnets should follow the format: snet---. To do this I used the regular expression:

[if(and(greaterOrEquals(length(split(field('name'), '-')), 0), equals(split(field('name'), '-')[0], 'snet')), if(and(greaterOrEquals(length(split(field('name'), '-')), 1), contains(parameters('unit'), split(field('name'), '-')[1])),  if(and(greaterOrEquals(length(split(field('name'), '-')), 2), contains(parameters('env'), split(field('name'), '-')[2])), 'isValid', 'Environment not accepted')]

This works as expected. However when I try to allow the creation of subnets with names like "AzureBastionSubnet", I get an error that the name should follow the format above mentioned.

Here is the code of the policy:

{
  "mode": "All",
  "policyRule": {
    "if": {
      "allOf": [
        {
          "equals": "Microsoft.Network/virtualNetworks/subnets",
          "field": "type"
        },
        {
          "anyOf": [
            {
              "value": "(equals(field('name'),'AzureBastionSubnet')",
              "notEquals": "true"
            },
            {
              "notEquals": "isValid",
              "value": "[if(and(greaterOrEquals(length(split(field('name'), '-')), 0), equals(split(field('name'), '-')[0], 'snet')), if(and(greaterOrEquals(length(split(field('name'), '-')), 1), contains(parameters('unit'), split(field('name'), '-')[1])),  if(and(greaterOrEquals(length(split(field('name'), '-')), 2), contains(parameters('env'), split(field('name'), '-')[2])), 'isValid', 'Environment not accepted')]"
            }
          ]
        }
      ]
    },
    "then": {
      "effect": "deny"
    }
  },
  "parameters": {
    "unit": {
      "type": "Array",
      "metadata": {
        "displayName": "unit",
        "description": null
      }
    },
    "env": {
      "type": "Array",
      "metadata": {
        "displayName": "env",
        "description": null
      }
    }
  }

}

Is there an issue on how I'm expressing that the value "AzureBastionSubnet" is also allowed?

Thank you in advance for the help.

Azure policy for naming conventions for subnets to start with "snet", but allow subnet names like AzureBastionSubnet

Here is the updated policy to create a subnet with a name starting with snet based on the unit and environment conditions, and also allowing specific names like AzureBastionSubnet. In my case, I have given the unit name as IT and the env as test in the parameters

    {
      "mode": "All",
      "policyRule": {
        "if": {
          "allOf": [
            {
              "equals": "Microsoft.Network/virtualNetworks/subnets",
              "field": "type"
            },
            {
              "not": {
                "allOf": [
                  {
                    "equals": "AzureBastionSubnet",
                    "field": "name"
                  },
                  {
                    "notEquals": "isValid",
                    "value": "[if(and(greaterOrEquals(length(split(field('name'), '-')), 1), equals(split(field('name'), '-')[0], 'snet'), contains(parameters('unit'), split(field('name'), '-')[1]), contains(parameters('env'), split(field('name'), '-')[2])), 'isValid', 'Environment not accepted')]"
                  }
                ]
              }
            }
          ]
        },
        "then": {
          "effect": "deny"
        }
      },
      "parameters": {
        "unit": {
          "type": "Array",
          "metadata": {
            "displayName": "unit",
            "description": null
          }
        },
        "env": {
          "type": "Array",
          "metadata": {
            "displayName": "env",
            "description": null
          }
        }
      }
    }

The policy allows the creation of a subnet only if the specified conditions are met. For example, 'snet-IT-test' is considered valid, while 'snet-IT-demo' is not valid. Similarly, 'AzureBastionSubnet' is valid, but 'AzureBastionSubnet1' is not valid. The policy allows subnet creation only under valid conditions; otherwise, it denies the creation of the subnet.

Subnet result in Portal