Krunner shows but hangs right after type any symbol, it looks like webengine issue or something related. I've trying to compile older version but it hangs as well so issue is some new configuration?
Qt WebEngine seems to be initialized from a plugin

No problem here on fully updated system. Have you tried omitting some of the choices in the config, it certainly responds much faster with some functions I don't require.
I must say the config window takes an awful long time to display.!

I'm on Build repo, before 5.69 and Plasma 5.18.4 it works. I don't see in the git log something suspicious.

#bvbfan. OK thought you might be.

It looks like some kind of cache generation, after that it works

6 days later

Since I did see the same issue (and fixed that one too by clearing the cache), I thought it is better to post the probable cause of this:
https://bugs.kde.org/show_bug.cgi?id=420549
I too see a significant slowdown in boot up and error messages regarding mounting filesystems. Testing here now with removing ktp-kded-module, that should be the cause of it all.

EDIT:
Patched ktp-kded-module is up.