Super late, but I figured it out because it happened again in a more recent comment. Lemmy seems to automatically change the links to https instead of http, even when http was explicitly included in the url. Somehow, xkcdsw is a completely different site on https than on http. If you copy the link into an external browser and remove the s, the link works as intended. I can only assume this is a behavior of the lemmy app(s), which is why it didn’t affect some users. Were you using jerboa?
Yeah, I suspect it’s a jerboa problem. I’ve posted about it on the jerboa community now.
Edit: Confirmed. Jerboa’s source code uses a plugin to force all links to be opened as https.