@GutPuncherKO The amount of people complaining about thumbnails is alarming... It makes think it's less likely the uploader's lack of determination to present good quality content, but rather an technical issue.
It's really improbable that all of a sudden everybody started to mass upload really low quality images. And when you put into the equation the fact that the upload tool has had multiple issues since the migration to a new domain, with many of said issues regarding to image uploads, it really looks unintentional and definitely something for the site administrators to investigate.