App icon reverted back to being non-adaptive

Since version 3 of VLC for Android, the app does no longer show its adaptive icon in the app drawer. Instead, one only sees the cone without the white background that was previously used to make the icon adaptive. In the app settings, however, the icon with the white background is used. I am using VLC 3.1.7 on my OnePlus 6T with Nova Launcher. However, this issue does not seem to be launcher dependent, since the OnePlus launcher has the same problem.

Since we already had an adaptive icon before, I suspect this to be some bug in the packaging of the app?