62k of base64 of a random stock image from Pexel https://pastebin.com/raw/tU5D1kuT, you can try it here https://base64.guru/tools/data-url-to-image

Proper SPAM and user/content management is an inevitable need for public chat. E.g. what makes HN chat readable and full of legal content is not comment length limit but all of the other more complex systems enabling efficient moderation.