The field description in user profiles has the type set to PARAM_CLEANHTML. That is wrong as that type should be used (if ever) for places that support plain or hyper text, nothing more. As description is a general rich text in any format (Markdown included), it must be treated as PARAM_RAW.

Steps to reproduce

1. Select plain text area as your preferred editor
2. Edit your profile
3. Choose Markdown as the format of the description field as type a text using markdown blackquote syntax as your description:

   My favourite quote reads:

   > Don't Believe Everything You Read On The Internet -- Thomas Jefferson

• Expected behaviour: As this is Markdown text, the blockquote character > is stored as such in the database and the text is displayed as blockquote.
• Actual behaviour: The character is escaped before writing to the database so that it is stored as HTML entity > and the Markdown syntax is lost.