Why does my InDesign-created image look blurry on PC but not on mobile?

Hi All

I’m displaying an image for our value propositions I created in InDesign displayed above the footer on my website, but it looks blurry when viewed on a PC. It looks fine on mobile though.

When exporting from InDesign I select optimize for web. The original image is 478px x 30px.

Has anyone had experience with this issue and hows to rectify it?

Many thanks!