@Azheki9182 I used "Similar" just now using the URL of the duplicate image hosted on Gelbooru, and it was able to pull up the other similar posts. From the post, it looks like you uploaded from a file, since there's no URL under the source. If you don't upload from URL, I don't believe the "Similar" button works.
I always use IQDB.org instead when checking to see if something is already uploaded.
