when i try to embed a pdf, not appear in the page

when i try to embed a pdf (uploaded in the wordpress media gallery)the pdf not appear in the page, the iframe is “white”.

probably because the plugin add “//docs.google.com/gview?embedded=true&url=” in the source url.

<iframe id="s_pdf_frame" src="//docs.google.com/gview?embedded=true&url=https://pizzakuadra.it/wp-content/uploads/sites/14/2019/12/Menu_weboptimize.pdf" style="float:left; padding:10px;width:100%; height:600px;" frameborder="0"></iframe>