I am using KDE Neon 5.8.7 and Yakuake 3.0.4. I would swear that in earlier versions of Yakuake, it was possible to auto-hide it when not in focus. That preference seems to have disappeared. Does anyone know how to get Yakuake to auto-hide at startup ,s o I don't have to F12 every time I start my computer? I of course have Yakuake set to start at login

There is an option called "Keep Window open when it loses focus".

Could that be it what you are looking for?