Mapbox radar issue

HTML

<!DOCTYPE html>
<html>
<head>
    <meta charset='utf-8' />
    <title>Animate a series of images</title>
    <meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
    <script src='https://api.tiles.mapbox.com/mapbox-gl-js/v0.54.0/mapbox-gl.js'></script>
    <link href='https://api.tiles.mapbox.com/mapbox-gl-js/v0.54.0/mapbox-gl.css' rel='stylesheet' />
    <style>
        body { margin:0; padding:0; }
        #map { position:absolute; top:0; bottom:0; width:100%; }
    </style>
</head>
<body>

<div id='map'></div>
<script>
mapboxgl.accessToken = 'pk.eyJ1IjoiZ2FzcGFyeWFuIiwiYSI6ImNqdmM3b3VyMDAwbzk0ZG82YXFkbGh4aHYifQ.45FOwdknsdm_pyNIaW9ZZQ';
var map = new mapboxgl.Map({
    container: 'map',
    style: 'mapbox://styles/mapbox/light-v9',
    maxZoom: 40,
    minZoom: 0,
    zoom: 7,
    center: [8.262591, 48.154258]
});

var frameCount = 5;
var currentImage = 0;

function getPath() {
    //return "https://maps.dwd.de/geoserver/dwd/wms?service=WMS&version=1.3.0&request=GetMap&layers=dwd:RX-Produkt&styles=&width=4096&height=4096&srs=EPSG:3857&bbox=230596.40272276622,5934337.07299266,1750026.7710981474,7343518.710858418&format=image/png&transparent=true";//" + currentImage + ".gif";
	return "https://maps.dwd.de/geoserver/dwd/wms?service=WMS&version=1.3.0&request=GetMap&layers=dwd:RX-Produkt&styles=&width=1024&height=1024&CRS=EPSG:3857&BBOX=614360.8293587392,5933210.01991552,1713821.866597408,7423590.537061271&format=image/png&transparent=true";
	//return "https://maps.dwd.de/geoserver/dwd/wms?service=WMS&version=1.3.0&request=GetMap&layers=dwd:RX-Produkt&styles=&bbox=-523.462,-4658.645,376.538,-3758.645&width=1024&height=1024&srs=EPSG:1000001&format=image/png&transparent=true";
}

map.on('load', function() {

	var westLongitude = 5.5188972;
	var eastLongitude = 15.3955238;	
	var southLatitude = 46.945667;
	var northLatitude = 55.3167777;		

	var topLeft = { lng: westLongitude, lat: northLatitude};
	var mTopLeft =...