After a recent update to KDE Plasma (not sure which one exactly, now on 6.6.4) the colours in my LibreOffice got somehow messed up. I have been using the Orchis theme for everything (Plasma, Kvantum, GTK). As shown in the screenshot, the contrast with the icons and text and background is too low, everything is too light, and it is hard to read. Changing to a dark colour scheme helps, but I didn’t want a dark colour scheme.
I’m answering my own question below for others to reference, since I managed to solve the issue.
