Modify variable value in script when clicking on a label

Good morning,

I'm working with a small script that runs when you click on label . By doing so, it activates or deactivates a checkbox type input, and based on this I want it to show one thing or another on the screen (if it has been subscribed or not).

The parameters are passed through AJAX so that the page is not reloaded, but I find that the variable in JS is not updated, it always has the same value, the funny thing is that the database updates it well

$agregar = $usuario;
$statement = $conexion->prepare("SELECT * FROM comentarios WHERE ID = :id");
$statement->execute(array(":id" => $hilo_asunto[0]['ID']));
$resultado_me_gusta = $statement->fetchAll();

$porciones = explode(";", $resultado_me_gusta[0]['suscritos']);

$contador = 0;

foreach ($porciones as $porcion) {
   if ($porcion ==  $agregar) {
      $contador++;
   }
}

if ($usuario != "null") {
   if ($contador == 0) {
      echo "<form class='' name='suscribe' id='suscribirse_" . $id . "' title='Suscripcion post' action='foro.php?foro=" . $foro ."&subforo=" . $subforo . "&hilo=Vamos%dale&ID=" . $id . "' method='post'>";
          echo "<input class='suscribe_box' type='checkbox' id='suscribe_" . $id . "' name='subs' checked>";
          echo "<label id='suscripcion_" . $id . "'  class='suscribirse' onclick='myFunction_suscribirse($id)' for='suscribirse_" . $id . "'>Suscribirse</label>";
          echo "<label id='suscripcion_oculto_" . $id . "'  class='label_oculto' onclick='myFunction_suscribirse($id)' for='suscribirse_" . $id . "'>Ya suscrito</label>";
   } else {
          echo "<form class='' name='suscribe' id='suscribirse_" . $id . "' title='Suscripcion post' action='foro.php?foro=" . $foro ."&subforo=" . $subforo . "&hilo=Vamos%dale&ID=" . $id . "' method='post'>";
          echo "<input class='suscribe_box' type='checkbox' id='suscribe_" . $id . "' name='subs' checked>";
          echo "<label id='suscripcion_" . $id . "'  class='label_oculto' onclick='myFunction_suscribirse($id)' for='suscribirse_" . $id . "'>Suscribirse</label>";
          echo "<label id='suscripcion_oculto_" . $id . "'  class='suscribirse' onclick='myFunction_suscribirse($id)' for='suscribirse_" . $id . "'>Ya suscrito</label>";
   }

   echo "</form>";

}

The script that runs:

<script>
        function myFunction_suscribirse(respuesta_id) {
            let suscribirse;
            var id_respuesta = respuesta_id;
               var d = document.getElementById("suscripcion_"+id_respuesta);
               var form = document.getElementById("suscribirse_"+id_respuesta);
               var respuesta_id = "respuesta_" + respuesta_id;

              if( $("#suscribe_"+id_respuesta).prop('checked') ) {
                  suscribirse = 1;
                  d.style.background = "transparent";
                  d.style.color = "#949494";
              } else {
                  suscribirse = 0;
                  form.style.background = "transparent";
              }

              console.log(suscribirse)

               $.ajax ({
                 type: 'POST',
                 url: 'proces_suscribe.php',
                 data: { "corazon": suscribirse, "id_respuesta":id_respuesta }
               });



          };
        </script>

At this point the variable suscribirse always has the value 1, when it should vary between 0 and 1 depending on whether the input of type checkbox is activated or not.

The file proces_suscribe.php:

<?php

session_start();

require 'admin/config.php';

try {
    $conexion = new PDO($bd_config['dbname'], $bd_config['usuario'], $bd_config['password'] );
} catch (Exception $e) {
    echo "Error: " . $e->getMessage();
}


$heart = isset($_POST['suscribirse'])? $_POST['suscribirse'] : 0;
$like_id = isset($_POST['id_respuesta'])? $_POST['id_respuesta'] : 0;

if ($conexion) {

    $statement = $conexion->prepare("SELECT * FROM comentarios WHERE ID = :id");
    $statement->execute(array(":id" => $like_id));
    $resultado_me_gusta = $statement->fetchAll();

    $agregar = $_SESSION['usuario'];
    $todos_suscritos = $resultado_me_gusta[0]['suscritos'];

    $porciones = explode(";", $resultado_me_gusta[0]['suscritos']);

    $contador = 0;

    foreach ($porciones as $porcion) {
        if ($porcion ==  $agregar) {
            $contador++;
        }
    }

    //SI CONTADOR ES DISTINTO A 0 SIGNIFICA QUE YA HA DADO ME GUSTA, CON LO QUE HRBÍA QUE QUITARLO DE LA BAES DE DATOS PORQUE YA NO LE GUSTA

    if ($contador == 0) {
        $todos_suscritos .= $agregar . ";";

        $statement = $conexion->prepare("UPDATE comentarios SET suscritos = :agregar WHERE id = $like_id");
        $statement->execute(array(":agregar" => $todos_suscritos));

        //hay que quitarle uno porque siempre cuenta un array vacío...

        echo "<p>Ya estás suscrito</p>";



    } else {

        $a_borrar = $agregar . ";";
        $todos_suscritos = str_replace("$a_borrar","", $todos_suscritos);

        $statement = $conexion->prepare("UPDATE comentarios SET suscritos = :agregar WHERE id = $like_id");
        $statement->execute(array(":agregar" => $todos_suscritos));


        //hay que quitarle uno porque siempre cuenta un array vacío...

        echo "<p class='suscribirse'>Suscribirse</p>";


    }

}

?>

By not getting the script variable modified correctly I can not make the page with the correct content reload.