STEPS TO REPRODUCE
- Go to a page with some Headings (e.g. Sandbox)
- Click the Edit button for a Heading (small 'Pencil' in the right side)
- Type the letter 'K'
The heading is replaced by the letter 'K'.
The current page is opened in Wiki Edit mode. The same happens when typing "O" (page switches to Object Mode editor) or other shortcut.
The issue reproduces also on XWiki 13.1 and could not be reproduced on XWiki 12.10.4 or 13.0.