From the The Keyword (Google’s Blog):
Now, when you search on Google Images, you may see a “Fact Check” label under the thumbnail image results. When you tap one of these results to view the image in a larger format, you’ll see a summary of the fact check that appears on the underlying web page. These labels may appear both for fact check articles about specific images and for fact check articles that include an image in the story.
Fact check labels appear on results that come from independent, authoritative sources on the web that meet our criteria. These sources rely on ClaimReview, an open method used by publishers to indicate fact check content to search engines. We already highlight fact checks on Search and in Google News to make this content easy to discover. YouTube also leverages ClaimReview to surface fact check information panels in Brazil, India and the U.S.