lemmy.world is a victim of an XSS attack right now and the hacker simply
injected a JavaScript redirection into the sidebar. It appears the Lemmy backend
does not escape HTML in the main sidebar. Not sure if this is also true for
community sidebars.
[https://sh.itjust.works/pictrs/image/707c0f16-3d5c-4888-b865-34228d968ee6.png]
At a guess your emoji is part of a a newer unicode table and something in the lemmy backend has an older version that doesn’t include it.