WordPress | Function | Get the post type the Taxonomy Term is related to

get_post_type_name_from_term.php

<?php
function get_post_type_name( $term_id ) {
	// Here we use the term id to identify the name of the post type the related taxonomy is registered to
	$term = get_term( $term_id );
	$taxonomy = $term->taxonomy;
	$tax_object = get_taxonomy( $taxonomy ); // Get the taxonomy object
	$post_types = $tax_object->object_type; // Get the object type (as an array) the taxonomy is registered to
	$post_type_object = get_post_type_object( $post_types[0] ); // Use the object type to get details on the object type
	$post_type_name = $post_type_object->labels->name; // Get the name label of the the object
	return $post_type_name;
}
?>

To get the Term ID whilst on a category archive page use this:

if( is_category() ) {
    $title = single_cat_title( '', false );
    $term = get_term_by('name', $title, 'category');
    $subtitle = get_post_type_name($term->term_id);
}