my start and end date always gives me my local time instead of selected date in the fullCalendar - Laravel

I am using FullCalendar, and when i select a square (date) i show a modal i insert info ( title , objectif .. etc) once I click on 'save changes' the event is added not to the selected date but to my current date!

( **I ll try to explain it more , I select for example the date 15-04-2022 and i insert my information and click 'save changes ' but the event is being added to my local date which is the 19-04-2022 ** )

MyReservations.blade.php

Add New Reservation

        <div class="modal-body">
            <!-- Room -->
            <select class="form-control" aria-label="Default select example"  id="room_id" required >
                <option selected>Select Room</option>
                @foreach($room as $items)
                    <option value="{{$items->id}}">{{$items->id}}</option>
                @endforeach

            </select>
            <br>
            <!--  Title -->


            <div class="input-group">
                <span class="input-group-text"> Title : </span>
                <input class="form-control" aria-label="Title"  id="title" required> </input>

            </div>
            <br>
            <!-- Objectif -->
            <div class="input-group">
                <span class="input-group-text">Objectif :</span>
                <textarea class="form-control" aria-label="Objectif"  id="objectif" required></textarea>
            </div>
            <br>

            <!-- Time -->

            <div class="input-group">
                <span class="input-group-text">TimeLine :</span>
                <select class="form-control" id="cre" required >
                    <option></option>

                    <option value="8:30-10:30">8.30-10.30</option>
                    <option value="10:30-12:30">10.30-12.30</option>
                    <option value="13:30-15:30">13.30-15.30</option>
                </select>
            </div>




        </div>
        <div class="modal-footer">
            <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
            <button type="button" id="submit" class="btn btn-primary">Save changes</button>
        </div>
    </div>
</div>

            <div id="calendar">

            </div>

        </div>
    </div>
</div>

<script>

    $(document).ready(function() {

        $.ajaxSetup({
            headers: {
                'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
            }
        });

        var events = @json($events);
       $('#calendar').fullCalendar({
            header:{
                left:'prev,next today',
                center:'title',
                right:'month, agendaWeek, agendaDay'
            },
            events: events,
            selectable:true,
            selectHelper:true,

            select: function(start, end, allDays) {
                    $('#ResModal').modal('toggle');
                $('#submit').click(function () {
                    var title = $("#title").val();
                    var objectif = $("#objectif").val();
                    var room_id = $("#room_id").val();
                    var cre = $("#cre").val();
                    var start = moment (start).format('YYYY-MM-DD');
                    var end = moment (end).format('YYYY-MM-DD');

                    $.ajax({
                        url: "{{route('MyReservations.store')}}",
                        type: "POST",
                        dataType: 'json',
                        data: {title: title, start: start, end: end, room_id: room_id, objectif: objectif ,cre: cre},
                        success: function (response)
                        {
                            $('#ResModal').modal('hide');
                            $('#calendar').fullCalendar('renderEvent', {
                                  'title' : response.title,
                                  'start' : response.start ,
                                  'end'   : response.end,
                              });
                        },


                    });


                });


            },

        })
    });

</script>

NOTE: it was working perfectly before I added: the cre as a column in my DB and in my blade, my controller ..etc

-- in my migration cre is type String --