On Linux and the BSDs, VECTORCRAFT_TITLEBAR=app now uses the app bar as the title bar with System Title Bar on. Before, System Title Bar kept the desktop's frame while the Preferences note said the variable chooses the title bar.
While the variable is set, Preferences dims System Title Bar, and the note that System Title Bar takes precedence over VectorCraft Title Bar on Every Desktop does not show. macOS and Windows do not read the variable.