Question about tc_post_metas filter

I’m trying to add the last updated date to the post metas, I’m aware of the option in the Customizer but it is a bit unwieldy and I’d rather not have it on the post lists as well.

So far I’ve managed to do it properly with the following code using the tc_author_meta filter:

add_filter( 'tc_author_meta' , 'add_the_updated_date');
function add_the_updated_date() {
    if (is_singular('post')) {
        return sprintf( '<span class="author vcard"><a class="url fn n" href="%1$s" title="%2$s" rel="author">%3$s</a></span>(last updated on" <time class="entry-date" datetime="%4$s">%5$s</time>)' ,
            esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ),
            esc_attr( sprintf( __( 'View all posts by %s' , 'customizr' ), get_the_author() ) ),
            get_the_author(),
            esc_attr( get_the_modified_date('c') ),
            get_the_modified_date('j M Y')
         );
    }
    else {
        return sprintf( '<span class="author vcard"><a class="url fn n" href="%1$s" title="%2$s" rel="author">%3$s</a></span>' ,
            esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ),
            esc_attr( sprintf( __( 'View all posts by %s' , 'customizr' ), get_the_author() ) ),
            get_the_author()
         );
    }
}

[actual code is more complicated but I stripped it down for simplicity]
The above works fine and is perfect (except that the added code is within the <span class="by-author"> tag). However, I’m trying to understand why the same editing technique doesn’t work when using the tc_post_metas filter instead. For example, the following code:

add_filter( 'tc_post_metas' , 'add_the_updated_date');
function add_the_updated_date() {
if (is_singular('post') ) {
           return sprintf( '<div class="entry-meta">%1$s(last updated on" <time class="entry-date" datetime="%2$s">%3$s</time>)</div>',
              apply_filters( 'tc_meta_utility_text', $_html , $_args ),
              esc_attr( get_the_modified_date('c') ),
      	      get_the_modified_date('j M Y')
            );
	} else {
           return sprintf( '<div class="entry-meta">%s</div>',
              apply_filters( 'tc_meta_utility_text', $_html , $_args )
            );
}
}

… doesn’t work as it does not print the %1$s. This is more of an academic question and I was just wondering why the editing worked with one filter but not the other.

Thanks for your time!