How i did it
The original SVG had the binary 0/1 grid in the magnifying glass as a pattern fill. That pattern wasn't visible when exported to PDF.
I've exported that layer to a bitmap image, reimported that bitmap to the svg and used inkscapes "Trace bitmap" function to convert that image to a path. Then I've deleted the original pattern and the imported bitmap image.
In osm_button.svg I've also converted the text to a path.