Hello Raph,
I am sorry for the delay of this reply.
It seems like the issue is caused by the photo name that contain comma ( , ). When these picture is uploaded to the amazon s3, the chrome will read this picture as unexpected document header thus returning the ERR_RESPONSE_HEADERS_MULTIPLE_CONTENT_DISPOSITION.
I've added some fix inside your /administrator/components/com_easysocial/includes/cron/hooks/storage.php where during file upload, easysocial will trim the comma and replace it with dash ( - ). Here is one picture that I've uploaded to your site with the comma as part of the name (wallpaperpackz16,sss,asd),
https://s3-eu-west-1.amazonaws.com/ultreiya/media/com_easysocial/photos/253/446/wallpaperpackz16-sss-asd_large.jpg .
Unfortunately for other image that are already broken, there is nothing we can do about it as the image is already uploaded to the amazon s3.