add_filter(
   'friends_feed_list_title',
    function(
        string $feed_title,
        Friends\User_Feed $feed,
        string $parser
    ) {
        // Your code here.
        return $feed_title;
    },
    10,
    3
);

apply_filters( 'friends_feed_list_title', $feed_title, $feed, $parser_slug )