why does my marker appear in the layerswitcher under a number

I receive the list of layers to use in a json.
To add them, I browse the json and add the layers in the overlaylayers.
Then, I want to materialize the coordinates passed to the page with a marker.
It is displayed correctly but instead of finding the name of the marker “Position” in the layerSwitcher, there is a number.
Below is the code to use.
Any idea?

jsonData.Layers.forEach(layer => {
    console.log("2 "+layer.Layer.nom);  // Affiche le nom de chaque layer

    index = index + 1;
    const layerKey = `lyr${index}`; // Créer une clé dynamique
    let [unLayer,unNom,unVisible]=createLayer(layer.Layer);
    theLayers[index]=unLayer;
    theLayersSwitcher[index]= {layer : unLayer, config : {title : unNom,description : unNom,visibility : unVisible}};

    theLayersNom[index]=unNom;
    theLayersVisible[index]=unVisible;

    if (layer.Layer.inUse==1)
    {
        overlayLayers[layer.Layer.nom] = unLayer; // Stocker la couche dans l'objet}
        unLayer.addTo(map);
    }
    else
    {
        overlayLayers[layer.Layer.nom] = unLayer; // Stocker la couche dans l'objet
    }
});
let PositionMarker = L.marker([<?php echo $_REQUEST["LATITUDE"]?>, <?php echo $_REQUEST["LONGITUDE"]?>], {
    title: "La position"
}).addTo(map);

let reversedLayersSwitcher = {};
let keys = Object.keys(theLayersSwitcher).reverse();
index = 0;

for (let i = 0; i < keys.length; i++) {
    index += 1;
    reversedLayersSwitcher[index] = theLayersSwitcher[keys[i]];
}

let layerSwitcher = L.geoportalControl.LayerSwitcher({ layers: reversedLayersSwitcher });
map.addControl(layerSwitcher);