Launchpad is a place to open applications, there is a search bar at the top, when you select an application to launch, the launchpad should disappear, you shouldn't still see the search bar.
Do you see the menu bar at the top of the screen when in Launchpad? Or after you select the app, because when launch pad opens the menu bar disappears, when you select the app the menu bar should come back and the launch pad should disappear.
I wonder if either
1. The launchpad is not closing correctly.
2. There is an accessibility option activated that is keeping it open for awhile.
You may want to read this to reset Launchpad ...
https://www.lifewire.com/fix-launchpad-problems-in-os-x-2259966