Laser does not cut what it should

Inkscape Path > Trace Bitmap using Centerline tracing (autotrace) results in the following for me:
Rastergrafik

“Centerline tracing” is the important part. It converts your drawing’s line into a single line that you can then edit in Lightburn. The resulting file will still need processing (delete some stray dots/short lines, close some shapes, as they are not closed in your original input image)