Environment version: .NET 9.0.0 (9.0.0)
Newtonsoft.Json version: Newtonsoft.Json, Version=12.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed

Re-serialized RootObject
{
  "data": [
    {
      "propertyNames": {
        "0": {
          "a": "a1",
          "b": "b1",
          "z": "z1"
        },
        "1": {
          "a": "a2",
          "b": "b2",
          "z": "z2"
        }
      },
      "otherProperty": "abc"
    },
    {
      "propertyNames": {
        "1": {
          "a": "a1",
          "b": "b1",
          "z": "z1"
        },
        "2": {
          "a": "a2",
          "b": "b2",
          "z": "z2"
        }
      },
      "otherProperty": "bce"
    }
  ]
}