I just noted this on my forum and also on this forum: when I try to save a cached image from forum, the image title includes the full path. You may test it here https://www.elkarte.net/community/index.php?topic=2681.msg36462#msg36462
just right click on the image and save the image.
I'm not sure is a bug or this is needed
I see the http image in the post linked by radu, maybe something went wrong while working on the server?
I had to turn off that addon, it was not compatible with php 7.4 so it needs an update.
I update the image_cache addon to fix the error that was filling up the log ... it should be fixed now as I re installed it here.