Either zip it or just rename it with a new file extension like dxf. Then the downloader can change it back.
But the picture version of the SVG on the forum should be downloadable as an SVG by using Chrome as the browser, right mouse click and “safe as” and it will download as an SVG.
My guess is you’ve got either disconnected or overlapping nodes there. I’m on my phone so I can’t download your file to check that, but it’s fairly common.