Right now Lemmy is unusable for writing code that contains less than/greater than signs because Lemmy's sanitizer treats that as potentially malicious HTML code.
Yeah I think this was hastily done to prevent the XSS injection attacks that were happening IIRC. They implemented encoding for content, but looks like they never got around to fully decoding it.
Issue could've been avoided by just restricting the encoding to when the user types content in (and before database insertion), and decoding when showing the content in the UI.