This is weird - completely random websites are being filled with Vietnamese Unicode "đ" characters. It's only an odd few sites: I first noticed it on https://arxiv.org/ (see image 1 below or https://i.imgur.com/UYnVYOO.png). I couldn't see it again so I assumed it was a problem with ArXiv, no other website seemed to be affected. Wikipedia, Google, news sites - all seemed to be fine. Today though I randomly came across two more: this one http://www.ferrolic.com/inquiries/ (see image 2 https://i.imgur.com/aphP4qL.png for what it looks like to me) and then any forum post made with phpBB (e.g. https://reactos.org/forum/viewtopic.php?f=2&t=18113 looks like image 3 or https://i.imgur.com/nP0PPXp.png). Any help or ideas? It's so completely random, I haven't come across any other sites - if anyone can find the link between them that would probably help. It's also notably only certain text boxes as shown in the forum link. Edit: here's another one, which randomly I discovered while serching for help with this post: https://forum.joomla.org/viewtopic.php?t=302052&start=30 (image 4)