am I the only one who gets different minizing animations from time to time?

e.g. currently I have to windows open one minimizes by moving to the corresponding place in the taskbar the other one just minimizes to the middle of the screen

Edit: also the taskbar settings don't create a seperate window

Nope, you aren't the only one. I filed a bug report about it.
https://bugs.kde.org/show_bug.cgi?id=334920