Lighthouse

Hello all, currently I have the following incident with the insertion of an image. I created a field with the type images and added it in a template. I used this template for a new page creation and uploaded a image there. Then I inserted the image using the image button. It looks like this (database and source button) <p><img alt="" src="/site/assets/files/1064/bild-gruen.1455x0-is.png" width="768" /></p> However, the following source code then appears on the server <p><img alt="" src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" width="768" class="image-width-control" data-src="/site/assets/files/1064/bild-gruen.1455x0-is.png"></p> Only an empty space appears instead of the image. If I debug the code here and replace it with the above code, then it works. I don't understand what I have set wrong or what is manipulating the code wrong. Can anyone help me solving this incident please? Thanks.