In Ubuntu 20.04 GNOME Flashback with Metacity, all windows had nice rounded corners like on the screen below:
When I switched to GNOME Flashback with Compiz, non-CSD windows (eg. Firefox or Synaptic) still have those rounded corners, but CSD windows (the ones used by default GNOME applications, like Nautilus) have lost them and now are sharp rectangles:
Is there any way to bring the rounded corners back?

