The bug
Some Arabic translations extend item tooltips.
How to reproduce
Select Arabic (first right-to-left language in languages list) as language
Switch to Creative mode and open your inventory
Hover over the brick icon of the "Building Blocks" tab
Linked issues
Attachments
Comments

Confirmed for 1.13.1. This issue is same as MC-117311.
No, it's not the same. This one is about the text extending the background, the other one is about the tooltip being left-aligned when it should be right-aligned (because it's a right-to-left language).

this is no longer an Issue in 1.16 rc-1

this is no longer an Issue in 20w28a, please change "open " to "RESOLVED"

Cannot reproduce anymore either.
Apparently, the width of the text is incorrectly calculated. This can also be seen in the pause menu with the "Open to LAN" button, where the text is incorrectly centered.