Gstatic is Google's content delivery service. Essentially it caches all 'static', or unchanging files in a server near to you in order to reduce load times. This means that some content on Google rather than displaying the source URL shows a Gstatic URL instead.

In Market Intelligence we rename gstatic.com to "Google Images" to help indicate how much share of voice the content is obtaining. Unfortunately, we don't know the source of this content without following the click.
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GStatic URLs appear predominately on mobile when the blocks have the following interactivity:
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As you can see the first image click doesn't actually take you to the website source.