Any time I post something, be it here on the forums, or in the homebrew section, any large form text field gets an image put into it. I'm not putting it there. I've attempted to delete it, and it just comes back when I refresh the page. 

This is the warning I get. 

This is the only site this happens on. Anyone know what to do about this?

Have you checking your device, browser or extensions?

This is very much a you/your device thing and not actually D&D Beyond (otherwise it would affect lots of people). Try testing with a different device, clear cookies and cache, log out and back in, turn off extensions, etc, etc.

This looks like some kind of extension, script, or add on in your browser is inserting the iframe. It could be anything from malicious code to an antivirus

I would suggest loading the site in a different browser, or incognito with no extensions etc running