It only becomes an image to me when outside of a code/preformatted block. Inside of one, it contains the raw markdown verbatim: <code class="hljs">!<span class="hljs-selector-attr">[alt]</span>(url)</code>.
I think that it’s the backend that screws the “url” up. Everything looks good in the preview, but the “url” part disappears upon publishing.
Looks like it’s using markdown-it, a Rust port of a JavaScript library with the same name.
It looks unmaintained. Last commit is from 2 years ago and issues look inactive. (including one asking asking about the maintenance status)
But it shouldn’t do that when enclosed in a code/preformatted block?
Nice alt text, very concise!
The syntax for images in markdown is 
.
Edit: Feels ridiculous to have to use a real image for this. Lemmy really seems to dislike image-like formatting in code blocks.
A hall of fame I kind of want to be in. Perhaps I should take up posting.
P.S. I noticed that your image is missing alt text. Something like “Long list of users who allegedly harass Rimu” would probably fit.
It’s our meme now, comrade!