SUMMARY
Second keyboard for second pointer (or input master) does not work even though the second keyboard is used to open kickoff (and the same thing happened to krunner), even when the second keyboard is used to start kickoff but only the first keyboard (in first input master) is able to type something. 

STEPS TO REPRODUCE
1. xinput create-master
2. xinput reattach (all the second mouse and keyboard) https://wiki.archlinux.org/index.php/Multi-pointer_X#xinput_utility
3. super (I binded it to alt-f1) from the second input master/keyboard
4. Type something from the second input master/keyboard

OBSERVED RESULT
Only the keyboard from first input master is able to type something, the second input master is not able to type anything, even if the second pointer is updated to use the first input master. The same thing is observed for krunner.

EXPECTED RESULT
Second keyboard from second input master should be able to search kickoff instead of the first keyboard from first input master since it is the one that initiated it, also the first keyboard should also be able to input if the if the first pointer clicked on kickoff search bar. Right now second keyboard can't even enter anything even if the second pointer clicked on the search bar. The same thing is expected from krunner.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Linux mi 5.10.6-zen1-1-zen #1 ZEN SMP PREEMPT Sat, 09 Jan 2021 18:22:39 +0000 x86_64 GNU/Linux
(available in About System)
Operating System: Arch Linux
KDE Plasma Version: 5.20.5
KDE Frameworks Version: 5.78.0
Qt Version: 5.15.2
Kernel Version: 5.10.6-zen1-1-zen
OS Type: 64-bit
Processors: 6 × AMD Ryzen 5 4500U with Radeon Graphics
Memory: 15.1 GiB of RAM
Graphics Processor: AMD RENOIR

ADDITIONAL INFORMATION
This happens to krunner as well.