When using the panel macro (or noformat, or code, etc.) before a table, switching to Wiki markup when using Rich Text editor as the default editor breaks table's header.

To replicate:

1. With Rich Text Editor as the default editor, create a page with the following content:

   {panel}Some content{panel}
   || row 1 || row 1 ||
   | row 2 | row 2 |
   

2. Save the page.
3. Edit again and switch to Wiki Markup editor.
4. Edit the content of the table.
5. Save the page.
6. Watch it break.