In GNOME Shell there is a darkish background for the Fast Settings menu, the calendar applet, and desktop notification– however in Ubuntu 23.10, “the default Yaru theme makes use of a lightweight model for GNOME Shell parts,” in line with the weblog OMG Free.
“However there is a new GNOME extension that permits you to change this with out affecting the remainder of your desktop…”
You may make GNOME Shell darkish in Ubuntu by turning the ‘Darkish Model’ toggle on however that additionally makes apps use a darkish theme too. Not everybody needs that; they need a ‘combined’ look… [I]f you wish to use darkish GNOME Shell parts in Ubuntu 23.10 with out utilizing the darkish mode desire (which, as stated, will flip your apps darkish too) then the Darkish Model GNOME extension is strictly what you want.
It solely works with Ubuntu 23.10 and GNOME 45.