Since nobody seems to see/understand the importance of this patch:
Should I go ahead and abandon this revision?

@pino, but you had just said that "KF5 plasma does not use qca, the code for that was dropped as dead/unmaintained".
I just thought in using OpenSSL directly because you said that.
So, should I use QCA or not?

@sandsmark and @ngraham, these are temporary files and the disk where they are located will be always mounted and the file will not exists anymore when the computer is powered off (if the Konsole wasn't killed).
We don't need to protect those files in case someone steals your computer or something like. If that was the case, then I agree that disk encryption is the solution and this patch is useless.
What we need is to protect those files from malicious applications running in your system. In that case, there is nothing what disk encryption could do to help us.

@hindenburg, I'm using Debian Buster and apt-cache shows that kde-runtime depends on libplasma3 that depends on libqca2.

I asked @frederico to run in an old notebook that he has with a Celeron u2300 1.2GHz running Debian Buster.
He used find in its home folder to test. After some time I asked him to scroll back and forth and tell if he noticed any difference.
Apparently he did not found any noticeable difference.