Multiple json objects to one json object in PowerShell getting extra quotation marks

I was trying to append multiple Json object in a single JSON Array using Powershell

From this answer I got the solution

$users = [System.Collections.ArrayList]::new();

 #calling some API in a loop Start

            $response = $json | ConvertTo-Json 
            $null = $data.Add($response);

 #calling some API in a loop End

    $result = @{ Data = $data};


    $result | ConvertTo-Json  | % { [System.Text.RegularExpressions.Regex]::Unescape($_) } | Out-File 'C:\Jay\inv\$filename.json'

For an instance Lets say the JSON Response from the API is like

{
    "host": "tet",
    "port": 443,
    "protocol": "http",
    "isPublic": false,
    "status": "READY",
    "startTime": 1585220081665,
    "testTime": 1585220127003,
    "engineVersion": "2.1.0",
    "criteriaVersion": "2009q",
    "endpoints": [
        {
            "delegation": 1
        }
    ]
}

Then as per the script my final file i was expecting like

{
    "Data" : [
        {
            "host": "tet",
            "port": 443,
            "protocol": "http",
            "isPublic": false,
            "status": "READY",
            "startTime": 1585220081665,
            "testTime": 1585220127003,
            "engineVersion": "2.1.0",
            "criteriaVersion": "2009q",
            "endpoints": [
                {
                    "delegation": 1
                }
            ]
        },
        {
            "host": "tet",
            "port": 443,
            "protocol": "http",
            "isPublic": false,
            "status": "READY",
            "startTime": 1585220081665,
            "testTime": 1585220127003,
            "engineVersion": "2.1.0",
            "criteriaVersion": "2009q",
            "endpoints": [
                {
                    "delegation": 1
                }
            ]
        }
    ]
}

But I'm getting additional quotation marks like below which makes the error in the json

{
    "Data" : [
        "{
            "host": "tet",
            "port": 443,
            "protocol": "http",
            "isPublic": false,
            "status": "READY",
            "startTime": 1585220081665,
            "testTime": 1585220127003,
            "engineVersion": "2.1.0",
            "criteriaVersion": "2009q",
            "endpoints": [
                {
                    "delegation": 1
                }
            ]
        }",
        "{
            "host": "tet",
            "port": 443,
            "protocol": "http",
            "isPublic": false,
            "status": "READY",
            "startTime": 1585220081665,
            "testTime": 1585220127003,
            "engineVersion": "2.1.0",
            "criteriaVersion": "2009q",
            "endpoints": [
                {
                    "delegation": 1
                }
            ]
        }"
    ]
}

Could someone help to find what is going wrong with the powershell script ?

Update 1

$result = @{ Data = $data | ConvertFrom-Json };

I'm getting the json like

{
    "Data" : [
        {
            "host": "tet",
            "port": 443,
            "protocol": "http",
            "isPublic": false,
            "status": "READY",
            "startTime": 1585220081665,
            "testTime": 1585220127003,
            "engineVersion": "2.1.0",
            "criteriaVersion": "2009q",
            "endpoints": "     "
            ]
        },
        {
            "host": "tet",
            "port": 443,
            "protocol": "http",
            "isPublic": false,
            "status": "READY",
            "startTime": 1585220081665,
            "testTime": 1585220127003,
            "engineVersion": "2.1.0",
            "criteriaVersion": "2009q",
            "endpoints": "     "
            ]
        }
    ]
}