gnome-session-flashback 1:3.36.1-1ubuntu1 (amd64 binary) in ubuntu focal

 GNOME Flashback continues the traditional desktop interface which was used
 in GNOME 2.x, but using modern GNOME technologies.
 .
 The key parts of GNOME Flashback are the GNOME Panel and the Metacity
 window manager. All other components, such as the file manager, the
 settings center, and the various applications, come from mainstream
 GNOME.
 .
 GNOME Flashback has lower hardware requirements than GNOME Shell, and
 consumes less memory.
 .
 This package provides the required components for the GNOME Flashback
 session. It can be started from a display manager such as GDM.