Hmm wlroots and sway seem to be in an odd spot. I think wlroots released a new breaking-change version and hyprland has updated to support those changes but sway hasn't, so Arch has split wlroots into two packages for the moment.
Not a fan of being hit with "Want to replace package foo with package foo0.18.0?" though because that usually precurses a small fire.
Gonna just give it a few days to see if the new sway RC mainlines.