SUMMARY
Kicker's search field defocuses when moving mouse through top-level menus or search results. Typing characters when the search box is defocused will focus the search box again and enter the character. Typing backspace or delete when the search box is defocused will only focus the text box again, and not delete any character. Furthermore, if search results appear under the mouse when typing, the search box immediately defocuses again.

EXPECTED RESULT
Search box should not ever defocus.

I suspect this is the same kind of bug as this one in krunner (https://bugs.kde.org/show_bug.cgi?id=444470). If so, this might be a bug with frameworks concerning the search box widget/control. I don't really know the software architecture of frameworks or plasma, though, so I might be mistaken

SOFTWARE/OS VERSIONS
Arch Linux
KDE Plasma Version: 5.24.5
KDE Frameworks Version: 5.94.0
Qt Version: 5.14.5
X11