The update of 2020.11.05 has broken the background of the items in the global menu widget of KDE Plasma when the Oxygen Plasma theme is used ─ see the screenshot below.
It does not misbehave this way with other Plasma themes, but the problem is that most of them are flat, opaque, lack shadows, or any combination thereof. There are a few nice ones, but unfortunately they make the text unreadable against a light background.
Also, other text items on the panel ─ e.g. the window title widget and the clock ─ do not suffer from this weird effect, so I’m guessing it must be something to do with the global menu widget specifically.
Now, I’m not an expert on scalable vector graphics, and I suspect that the Plasma themes are written as SVGs. So, if any of you theme experts out there would be willing to offer a clue that allows me to fix this, I would appreciate it.