Please feel free to tag this security.

I recently accidentally typed a password into krunner. After that, I was
able to recall the password in full-length clear-text by just typing the
first character of the password into krunner. In Krunner Settings, there
is a "Clear History" button. After pressing this, I was still able to
recall the password in the same way. It was necessary to kill and
restart krunner to make that password go away.

Greetings
Marc