I've created a map with Leaflet and jQuery and I wanted to add Clustergroups to my Markers but I am getting the error : leaflet.js:5 Uncaught TypeError: Cannot read properties of undefined (reading 'trim')

Here my code:

  $.get(url).done(function (data) {


            var markers = L.markerClusterGroup();
            for (let i = 0; i < data.length; i++) {
                var title = "hi";

                let marker = L.marker(([data[i].latitude, data[i].longitude]));
                marker.bindPopup(title);
                markers.addLayer(marker);
               
            }
            mymap.addLayer(markers);

        }

I tried to search for the problem and found this https://github.com/Leaflet/Leaflet.markercluster/issues/724 but the problem was never answered. Also i read about different types of problems that it is maybe the problem of jQuery that it cannot define the variables. But I dont't know where my mistake could be, can anyone see it? Thanks in advance