In Ubuntu 21.10, the decision has been made to discontinue the theme that combines dark headers, a light background, and light controls. Users will be offered the fully light version of the Yaru theme by default, with the option to switch to a fully dark version (dark headers, dark background, and dark controls).
This decision stems from the lack of support in GTK3 and GTK4 for different background and text colors for the header and main window, which prevents all GTK applications from functioning correctly when using combined themes (for example, in gnome disk analyser, a white input field appears under a dark header). Another reason is the excessive labor required to maintain non-standard themes. The issue is that GNOME does not provide an official API and guidelines for GTK themes, leading to compatibility breaks with third-party themes in each new GNOME release.
Tra le altre modifiche previste in Ubuntu 21.10, si segnala l'abbandono del colore melanzana per lo sfondo degli switch e dei widget (il colore sostitutivo non è ancora stato approvato).
Fonte: opennet.ru
