Context: Voyager shows these options which results in a large amount of reports just being "Breaks community rules" with no info or reason whatsoever.
It's been a while, but I think it's based on a trick to add comments to Markdown. I tried it with Tesseract, and none of the lines rendered, but only if I add an empty line in front.
It's a bit of a hack, but it can use existing endpoints and only needs some minor changes on the client side. The alternative would be implementing support for it in Lemmy, Mbin, PieFed, etc. but that probably takes a while and can also be done later when it has proven its usefulness.
Edit: I think I found the explanation behind the syntax https://stackoverflow.com/questions/4823468/comments-in-markdown