In Slack you get syntax highlighting if you use /snippet instead of Markdown fences, but everything else supports Markdown fences, so it seems dumb Slack doesn't and you have to discover a random slash command to do it. Similarly it bugs me that Slack's Markdown uses a different definition of italics and bold than CommonMark and most everyone else. I know the biggest standard of Markdown is that there is no real standard, but Slack's Markdown sure is less standard than normal.