The GNOME Shell 40 Beta brings its redesign to the overview area, out-of-date extensions are now disabled by default, and a wide variety of fixes ranging from crash fixes to general bug fixes.
The full list of GNOME Shell 40 Beta changes can be found via GNOME's Gitlab .
The Mutter 40 Beta changes are also interesting with it now defaulting to starting XWayland on-demand , support for atomic mode-setting , defaulting to the horizontal workspace layout , improved touch mode heuristics, and a variety of other fixes. More details on the Mutter 40 beta changes via this Git commit .