QTextMarkdownWriter fails to escape special characters at the beginnings of blocks, most notably '-', '*', '+' and '#' and generally fails to escape special characters like '\' and '`', causing ordinary characters to be treated as markup when reading back the generated markdown code.

The failure to escape initial characters in a block is surprising, because there is code to escape the first character when wrapping text, which is a much less common case (see the static function maybeEscapeFirstChar and where it is called).

The text "+ and - are arithmetic operations" is written out verbatim, so when it is read back in as markdown, it shows as a list item:

• and - are arithmetic operations

Similarly, when the text "# is next to 0 on your phone keypad" is read back as markdown, it is treated as a heading and looks like this:

is next to 0 on your phone keypad

The text "Use two backslashes <backslash><backslash> to separate fields." (with <backslash> replaced by a backslash character - ironically, the Jira visual editor does not allow me to enter two backslashes) is exported verbatim and when read back becomes:

Use two backslashes \ to separate fields.

I have tested this with Qt 5.15.2, but from looking at the source code, there seems to be no change since then, so I expect this to still be broken in the current Qt6 releases.