Requires Violentmonkey or compatible userscript manager.
Click here to install
There's a bug where the file hash returned by the site's API doesn't match the actual file.
If such an image was downloaded from Site A then uploaded to Site B. Trying to search for the image from Site A would find no result. As a workaround, you can ctrl + click the link again to force the script to download the full image and compute the hash client side.
This let you search on Site A for images that had been uploaded to Site B. However, it won't work for the inverse, i.e. find the source image on Site A from Site B. So, when client-side hashing fails to yield result, the script uses Philomena's reverse image search function as the final fallback.