Fix #3675 - Adjust quality settings of converted GIFs to reduce filesize (#3723)

app/models/media_attachment.rb

@@ -88,7 +88,8 @@ class MediaAttachment < ApplicationRecord
                 'vsync'    => 'cfr',
                 'b:v'      => '1300K',
                 'maxrate'  => '500K',
-                'crf'      => 6,
+                'bufsize'  => '1300K',
+                'crf'      => 18,
               },
             },
           },