IndieBlocks’ Facepile block will, as of the yet-to-be-released next version, support the Webmention plugin (i.e., Webmention v5.0 and up). https://github.com/janboddez/indieblocks/blob/ce87daf8eb157ca6a6c13200281e3c7976fb752a/includes/class-blocks.php#L448
There’s no way to turn that off, which I think is OK.
Remember: you don’t actually need a separate Webmention plugin, but if you use and like the Webmention plugin, consider giving the Facepile block a chance.
Come to think of it, I’ve yet to test non-facepiled webmentions.
