It seems that Mastodon has issues with HTML in summaries (#893)

Fixes: mastodon/mastodon#28455

Until this is merged: mastodon/mastodon#28629

Author: pfefferle

includes/class-hashtag.php

@@ -28,9 +28,11 @@ public static function init() {
 	 * @return array the activity object array
 	 */
 	public static function filter_activity_object( $object_array ) {
+		/* Removed until this is merged: https://github.com/mastodon/mastodon/pull/28629
 		if ( ! empty( $object_array['summary'] ) ) {
 			$object_array['summary'] = self::the_content( $object_array['summary'] );
 		}
+		*/
 
 		if ( ! empty( $object_array['content'] ) ) {
 			$object_array['content'] = self::the_content( $object_array['content'] );

includes/class-link.php

@@ -24,9 +24,11 @@ public static function init() {
 	 * @return array the activity object array
 	 */
 	public static function filter_activity_object( $object_array ) {
+		/* Removed until this is merged: https://github.com/mastodon/mastodon/pull/28629
 		if ( ! empty( $object_array['summary'] ) ) {
 			$object_array['summary'] = self::the_content( $object_array['summary'] );
 		}
+		*/
 
 		if ( ! empty( $object_array['content'] ) ) {
 			$object_array['content'] = self::the_content( $object_array['content'] );

includes/functions.php

@@ -1211,5 +1211,8 @@ function generate_post_summary( $post, $length = 500 ) {
 		$content = $content[0] . ' ' . $excerpt_more;
 	}
 
+	/* Removed until this is merged: https://github.com/mastodon/mastodon/pull/28629
 	return \apply_filters( 'the_excerpt', $content );
+	*/
+	return $content;
 }