After many many years I just decided to give KDE/Plasma another chance and installed it alongside my usual window managers (xfce, mate) on my Ubuntu 22.04.1 (all updates installed as of today) laptop which has a display resolution of 2880x1620. With Mate and XFCE, everything is getting displayed fine, the display configuration is set to 200% scaling.

Plasmashell reports version 5.24.4

However, with Plasma, window decorations are tiny and way too small while other interface elements are ok or too big. This is the case for native KDE applications too, e.g. with konsole: the window decorations are tiny, but the icons in the menu bar (?? what it is this even?) are way too big.
I would have liked to attach a screenshot to this post but could not find out how to do this.

As I said, scaling is set to 200% in the display configuation dialog. What else can be done to fix this?

Weirdly, when running the same KDE apps in the MATE display manager (e.g. konsole), window decorations and the window content itself both render correctly.

Is there a better place to get help with this (e.g. one that actually allows to attach screenshots to better share information about the problem)?