When upgrading from budgie-desktop 10.7.2-5 to 10.7.2-6, the package mutter43 must be replaced with magpie-wm, which currently depends on mutter. As mutter43 conflicts with mutter, manual intervention is required to complete the upgrade.
First, remove mutter43 via "pacman -Rdd mutter43", then immediately perform the upgrade via "pacman -Syu". Do not relog or reboot between these steps. This will bypass the conflict.