It looks like the link is fine when clicked by the recipient, but the preview comes up as 404. Either fb/wa is doing something odd in the request when generati

It looks like the link is fine when clicked by the recipient, but the preview comes up as 404. Either fb/wa is doing something odd in the request when generating the preview, or the other end is responding badly to something unusual-but-correct that there's are doing. Perhaps due to the initial request's accept headers a redirect is being sent instead of the usual content, and requesting that results in a 404. Could be malicious as many are suggesting, I certainly wouldn't put it past them, but I suspect cockup is a more likely explanation.