Oh I did not know that python3-six was an very old package that is going to be removed from Debian because of this until I saw the last line in your message. That explains why Debian have not included it with Cinnamon install. You also said that Python3-pam is also an older package.
I have not yet tried Cinnamon with Python3-pampy. So I don't know if just installing that will resolve the problem with the Cinnamon control Center not ruining. But installing the other two programs does. The Cinnamon Desktop is made by Linux Mint who have their own custom programs and apps. And the updated version of Cinnamon which is 6.4.1 on Debian Sid and Debian Testing is the lame version that is on Linux Mint. Except that some of the customisations and programs in the Debian are not the same as on Mint. Also worth noting is that the Linux Mint used the Mate Panel in their version of Cinnamon including 6.4.1 as a dependency of Cinnamon . But Debian does not. The Mint version of Cinnamon depends on either Gnome flashback or Mate Panel in order to run the desktop. This was also the case in earlier versions of Debian Cinnamon but not on Cinnamon 6 and later versions. So I don't think that is the reason why Cinnamon Control Center won't work without python3-six. Although Linux mint may be using different programs from python3-six as their dependencies. Debian users who are on Debian Sid or Debian Testing will just have to use the temporary fix of installing python3-six or python3-pam on the Cinnamon Desktop until this problem is sorted out by Debian. *Andrea Borman.*
