Preview images downloaded as .ai instead of jpg

Recently, anytime I download a preview image for a vector file, it comes as an .ai format.  Mind you, it's a bitmap placed into an Illustrator document, but it's not sized to fit on the artboard, and it's over-pixelated.

I'm not sure who would choose this option intentionally, but I would like to reset my settings to always download previews as JPGs, regardless of whether they are vectors or not.  Any ideas?