[tag:status-norepro] on my side:

[![s1][1]][1]

[![s2][2]][2]

When you send \`---Strike---\` the message is temporarily shown as <del>Strike</del> before updating and becoming `---Strike---`; I suspect auchatstatus or some other userscript / Javascript related thing on your client interfering with this update.

  [1]: https://i.sstatic.net/LM5p6.png
  [2]: https://i.sstatic.net/jNxwn.png