Created attachment 134404 [details]
screenshot of the described behaviour after pressing "kaf"

SUMMARY

When application name is typed in quickly the first time after KDE login, kickoff finds it but doesn't highlight/select it. So simply pressing Enter to start it immediately is not possible.

STEPS TO REPRODUCE
1. login to a new KDE session (!)
2. open kickoff (I clicked the KDE plasma icon in the lower left corner)
3. quickly (!) type three letters ("kaf" in my case to select the kaffeine application)


OBSERVED RESULT

a) After typing the three letters "kaf" nothing is highlighted/selected although "kaffeine" is now the only entry in the list. kickoff already lists kaffeine after typing the first letter "k" (together with other applications starting with "k", see below).

I attached a screenshot.

After opening the kickoff menu a second time it is selected:

b) Open menu, press k: kaffeine, konsole and kate are found, nothing selected (???)
c) Open menu, press ka: kaffeine and kate are found, kaffeine is selected
d) Open menu, press kaf: kaffeine is found and selected


EXPECTED RESULT

If kaffeine is the only entry in the list it should be highlighted/selected automatically.


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Gentoo Linux
(available in About System)
KDE Plasma Version: 5.19.5
KDE Frameworks Version: 5.74.0
Qt Version: 5.15.1

ADDITIONAL INFORMATION