this is somehow related to the Rails Engine being mounted. Its was very hard to debug when I started looking adding it.
You should be able to reproduce this here somehow as well, since we are using akismet. Even if you bypass the cdn for the links
EDIT
@eviltrout header appears to be missing here https://meta.discourse.org//cdck-file-uploads-global.s3.dualstack.us-west-2.amazonaws.com/meta/original/3X/d/9/d9988c49657be1d3ade114885f695a1aa25f71ef.gif