/**
 * Allow plugins to disable block editor support,
 * thus disabling blocks registered by the Webmentions plugin.
 *
 * @param Webmention\boolean $supports_blocks 
 * @return Webmention\boolean The filtered value.
 */
function my_webmention_site_supports_blocks_callback( Webmention\boolean $supports_blocks ) {
    // Your code here.
    return $supports_blocks;
}
add_filter( 'webmention_site_supports_blocks', 'my_webmention_site_supports_blocks_callback' );

apply_filters( 'webmention_site_supports_blocks', $return )