How to stop the icon jumping effect in kubuntu?

Application Launch Feedback

KDE Help Center - Launch Feedback:

Sometimes it is reassuring to know that your computer didn't just ignore your command, and something is happening behind the scenes. In this module you can configure visible feedback to help you know if you really hit that icon or not.

The traditional way to indicate that your computer is busy is to modify the cursor, and you can turn this on by choosing a Busy Cursor. With this option enabled, your cursor will have an icon attached to it for a short time, when a new application is being launched. You can configure how long this icon is displayed beside your cursor with the Startup indication timeout: spinbox. The default is 5 seconds.

There are several variations of busy cursor available, including a Blinking Cursor, a Bouncing Cursor or a Passive Busy Cursor icon with no animation...

KDE System Settings > Personalization - Applications > Launch Feedback

As a single KDE control module

kcmshell5 kcmlaunch