Someone comments on a post now has On chips for the platforms the comments come from. An automation runs only on comments from the platforms it is on; automations made before stay on all of them. On the canvas the same choice is Comments on.
Where should it run? then lists only the accounts of those platforms.
A step none of the chosen platforms has is refused when you save, with the reason — for example, Send a DM works on Instagram and Facebook only. Before, it was skipped on every comment without a word.