The black sidebar to the left of my screen is all black with only the red WA logo at the top. However, when I hover over where I know specific buttons should be, I see the label pop up per usual beside it and when I click on the buttons, they are functional. It's the same for the toolbar in the editing screen. It's ONLY for the symbols, though. Buttons that simply have words on them (like the ones in the top central taskbar) are unaffected. The buttons in the upper right taskbar (help, notifications) are also invisible, but I still see the little red circle indicating how many notifications I have. This problem only started within the last hour.
I'm not sure how to reproduce it. It just started happening. I closed out of everything but it still happened. I logged out but it still happened. Next step, I guess, would be to restart my computer, but it's only a problem on World Anvil and nowhere else.
Having the same problem on macOS. This is definitely a bug with the new UI.