How to retrieve and display text from AJAX Response in SweetAlert using JavaScript and PHP

In the SweetAlert located in “kardex.js”, I am receiving this for some reason on the server:

[]{"justification":"Hello"} 

And I want to receive only the text that corresponds to “justification”, which in this case is “Hello”, and display it on this part:

text: 'Justification: ' + response,

Please consider that I am not very proficient in JavaScript. Thank you in advance.

I have four segments of 4 files that are related to each other.

First, here is “kardex.js”:

if(info.event.title === "OMISSION")
{
  getJustification(info.event.id, function(response)
  {
    Swal.fire(
    {
      title: 'Delete omission event?',
      text: 'Justification: ' + response,
      icon: 'warning',
      showCancelButton: true,
      confirmButtonText: 'Yes, delete',
      cancelButtonText: 'Cancel'
    }).then((result) => 
    {
      if (result.isConfirmed)
      {
        delete(info.event.id);
      }
    });
  });
}

Next is “omission.ajax.js”:

function getJustification(eventId, callback) 
{
  $.ajax(
  {
    type: 'POST',
    url: 'controller/omission.controller.php',
    data: 
    {
      accion: 'justification',
      eventId: eventId
    },
    success: function(response) 
    {
      callback(response);
    }
  });
}

Then “omission.controller.php”:

<?php

require_once "../model/omission.model.php";

class Controller
{
    public static function manageRequest()
    {
        $response= array();

        if ($_SERVER["REQUEST_METHOD"] == "POST") 
        {
            $table= "omission";
                           
            if (isset($_POST["action"]) && $_POST["action"] == "justification") 
            {
                $eventId = $_POST["eventId"];
                
                $response= Model::getJustification($table, $eventId);
            }
        }

        echo json_encode($response);
    }
}

Controller::manageRequest();
?>

Finally, “omission.model.php”:

<?php
require_once "db.php";

class Model
{
  public static function getJustification($table, $eventId)
  {
    $conn = connection::connect();

    // Get justification
    $stmt = $conn->prepare("SELECT justification FROM $table WHERE id = :id");
    $stmt->bindParam(":id", $eventId, PDO::PARAM_INT);
    $stmt->execute();
    
    $responose = $stmt->fetch(PDO::FETCH_ASSOC);
    
    return $response; 
  }
}
?>

What am I doing wrong? I have tried changing “response” to “response.justification”, but that gives me an error.