Don’t know if this is a known thing or not, but reporting it anyway.
It appears Markdown and BBCode aren’t parsed inside spoiler
tags:
[spoiler]Hello **Discourse** peeps![/spoiler]
[spoiler]Hello [b]Discourse[/b] peeps![/spoiler]
[spoiler]Hello <b>Discourse</b> peeps![/spoiler]
[spoiler]
Hello **Discourse** peeps!
[/spoiler]
[spoiler]
Hello [b]Discourse[/b] peeps!
[/spoiler]
[spoiler]
Hello <b>Discourse</b> peeps!
[/spoiler]
Hello Discourse peeps!
Hello Discourse peeps!
Hello Discourse peeps!
Hello Discourse peeps!
Hello Discourse peeps!
Hello Discourse peeps!