The Mate Panel or Gnome Flashback Desktop which had the Gnome Panel was installed in older versions of Cinnamon as a fallback. So that if the Cinnamon Desktop crashed then you would still have a working desktop. But this is not required on the the new versions of Cinnamon or on Cinnamon 6 because it doesn't need it. Although Linux Mint still includes the Mate Panel both their LMDE6 and 21.1 desktop both of which have Cinnamon 6.4.1.
On Linux Mint if you uninstall the Mate Panel on cinnamon then Gnome Session Flashback automatically gets installed as the fallback instead! But this is not the case on Debian but the Linux Mint version of Cinnamon 6.4.1 may have their own libraries. Because when I tried Cinnamon on Linux Mint the Control Center and everything worked fine. Maybe they do use phython3-six but I am not sure. *Andrea Borman.*
