According to man 5 sway-output:
output
power on|off|toggle Turns on or off the specified output.
As opposed to the enable and disable commands, the output keeps its current workspaces and windows.
output
dpms on|off|toggle Deprecated. Alias for power.
I have no idea how long that was, just noticed the update. Well, thankfully nothing is broken, but I updated my configs.
So,
:%s/dpms/power/g
it would be.