Wikimedia Commons has media related to Images with inappropriate JPEG compression.

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These images were uploaded in the JPEG format even though they contain non-photographic information. It is suggested that the original sources be revisited and that a PNG or SVG file without compression artifacts be uploaded in their places. For more information, see Wikipedia:Preparing images for upload. Images can be added to this category by placing the ((Bad JPEG)) template on the image description page. Computer and video game screenshots should be tagged with ((Should be PNG)). Note: If the image is copyrighted, it should not be rendered any larger than is required for the purposes of identification and/or critical commentary.