Only show modified date if updated after a month (or later)

Hello! I am using this code to show both the published and modified date on my blogposts:

function astra_post_date()
{
 $format = apply_filters('astra_post_date_format', '');
 $published = esc_html(get_the_date($format));
 $modified = esc_html(get_the_modified_date($format));

 $output = '<p class="posted-on">';
 $output .= 'Gepubliceerd op: <span class="published" ';
 $output .= 'itemprop="datePublished">' . $published;
 $output .= '</span><br>';
 $output .= 'Laatst bijgewerkt op: <span class="updated" ';
 $output .= 'itemprop="dateModified">' . $modified . '</span>';
 $output .= '</p>';}
 
 return apply_filters('astra_post_date', $output);

add_filter('astra_single_post_meta', 'custom_post_meta');
function custom_post_meta($old_meta)
{
 $post_meta = astra_get_option('blog-single-meta');
 if (!$post_meta) return $old_meta;
 
 $new_output = astra_get_post_meta($post_meta, "");
 if (!$new_output) return $old_meta;
 
 return "<div class='entry-meta'>$new_output</div>";
}

However, I would like to only show the modified date if the blogpost was updated 1 month after publishing.

So if I publish a post on 1 feb, and update it on 6 feb, it won’t show ‘updated on’.

But if I publish it on 1 feb and update it on march 1 or later, it will.

P.S. I got this code from some other page (I don’t remember) because I don’t know anything about javascript, so please explain in layman’s terms.

The page I need help with: [log in to see the link]