VLC plays videos in odd second window

When I open a file using VLC, I get two different windows: one with controls and one with just the movie playing. It's not a persistent problem. If I click on the main window quickly enough after opening the file, then the second window won't appear. But if I hesitate and don't click within the first half second after launching the file, then the second window will show up. Just to be clear, it is not a problem with multiple instances of the app; or multiple 'real' windows. It is a bizarre second basic window as shown below, which has no toolbar, titlebar or anything else to identify it as a VLC window. But my favorite part is that resizing the proper VLC window (the one with toolbar, titlebar, etc) actually also resizes the weird window. So they are linked, and the weird window 'thinks' it is inside the main app window.

The problem first appeared after installing VLC (tried software center installation, and command line installation; both installations produce the same bug) as first program on a fresh set-up of Ubuntu (Ubuntu 20.04.3 LTS; Gnome Version: 3.36.8; Windowing System: X11) on my PC (AMD® Ryzen 9 3900x 12-core processor × 24; with Nvidia graphics). Re-installing VLC does not fix the bug. Yet, running VLC on Windows on the same PC does not reproduce the bug.