When drafting Jira descriptions, comments, or acceptance criteria for a Text input field, use Atlassian wiki markup rather than ordinary Markdown. In particular, bullets start with *; headings use h1. through h6.; numbered lists use #; and monospaced inline text uses {{text}}.
When giving Jira-ready text in chat, enclose it in a fenced plain-text block. Otherwise the chat renderer may consume the literal * characters and display visual bullets, making the text unsuitable for direct copying into Jira Text mode.
Use the field's Text-mode ? Help control for the exact notation enabled on that Jira instance; renderers and macros can vary by field and configuration.
Official reference: Atlassian — Editing and collaborating on issues
Renderer details: Atlassian — Configuring renderers