mate-session-manager-1.24.2-1-x86_64.pkg.tar.zst was upgraded to mate-session-manager-1.24.3-1-x86_64.pkg.tar.zst
After rebooting the shutdown button did not work (it had before) and I could only choose to log out of the Mate desktop using the Mate GUI options. Downgrading mate-session-manager saw things work normally after # poweroff and rebooting. Don't know if it's just some peculiarity of my system or a more general issue.
thanks for report,
mate's maintainer in last update broke it, i fixed it now in mate-session-manager-1.24.3-1.1 . should works again!
Thank you for the rapid repair, it's all working properly again and shutting down on the button. ;D