On the Pages Menu, there is a tree of pages. If you get too deep into that tree, the title of the pages gets cut off.
This is the default behaviour of the page list, currently, the character limit of the list of pages cannot be edited or changed, this is by design and in order for other settings in the menu would still be shown or visible, especially on smaller screens or lower resolutions.
If the user would like to submit an enhancement request, they can visit:
Zhadd La Plana