Assistance requiring approach to a project

So I tried implementing the manual incremental refresh logic. With some help from ChatGPT I came up with this code,

=let
    // Step 1: Retrieve the previously stored data
    storedData = Table.FromRecords({}),
    // Function to fetch data from the API
    FetchDataFromAPI = () => 
    let
        // Define the URL of the API endpoint
        apiUrl = "https://worldtimeapi.org/api/timezone/Asia/Kolkata",
        
        // Make the HTTP request to fetch data from the API
        apiResponse = Web.Contents(apiUrl),
        
        // Convert the JSON response to a table
        apiDa = Json.Document(apiResponse),
        
         apiData = 
            if Value.Is(apiDa, type list) then
                apiDa // Return the list of records as is
            else
                {apiDa} // Wrap the single record in a list
    in
        apiData,
    // Step 2: Fetch data from the API
    apiDa = FetchDataFromAPI(),
    apiData=Table.FromRecords(apiDa),
    finalData=
        if Table.RowCount(storedData)=0 then
            apiData
        else
            let
                    // Step 3: Identify updates
                    updatedData = Table.Join(storedData, {"unixtime"}, apiData, {"unixtime"}, JoinKind.LeftOuter),
                    updatedDataFiltered = Table.SelectRows(updatedData, each [unixtime] <> null),

                    // Step 4: Merge updates with the stored data
                    mergedData = Table.Combine({Table.RemoveColumns(storedData, {"unixtime"}), updatedDataFiltered}),

                    // Step 5: Append new rows
                    newRows = Table.SelectRows(apiData, each not List.Contains(Table.Column(mergedData, "unixtime"), [unixtime])),
                    finalMergedData = Table.Combine({mergedData, newRows})
                in
                    finalMergedData
in
    finalData

The API is a publicly available API that gives the current time and date. An example is

{
    "abbreviation": "IST",
    "client_ip": "122.176.65.95",
    "datetime": "2024-04-01T15:03:59.624664+05:30",
    "day_of_week": 1,
    "day_of_year": 92,
    "dst": false,
    "dst_from": null,
    "dst_offset": 0,
    "dst_until": null,
    "raw_offset": 19800,
    "timezone": "Asia/Kolkata",
    "unixtime": 1711964039,
    "utc_datetime": "2024-04-01T09:33:59.624664+00:00",
    "utc_offset": "+05:30",
    "week_number": 14
}

My logic behind this code is that whenever I click on the "Refresh Preview" button in the Power Query editor, a new response would come, which would check with the "unixtime" field. Now this field would change with every call, so, every new record will be unique. So, according to my code logic, after every refresh, a new row would be added to the previous table. But that did not happen, instead the same row kept on updating. I don't understand where I am going wrong here. In another post Inserting rows recursively does not yield correct results , I found the point of #"Burndown Query", but didn't really understand it. Any help regarding the code would be much appreciated.

Thanks!