Problem displaying custom post type at home page

Hello, i’ve spent around 5 hours and can’t find a solution or help for my problem.
Maybe it is a simple issue, but i’m not a programmer ??

This is the situation:

I have a custom post type called dd-product. I also have a custom taxonomy called productcat.

Now, in my home page i’m showing all posts from dd-product post type. For this, i’m using this code in my functions.php file:

add_filter( 'pre_get_posts', 'my_get_posts' );

function my_get_posts( $query ) {

	if ( is_home() && $query->is_main_query() )
		$query->set( 'post_type', array( 'dd-product' ) );

	return $query;
}

What i want to do is to make a little bit different the posts from productcat category/taxonomy. Specifically, i want to change the title color for those posts with css (i have no problem with css)

I’ve tried with ‘if in_category’ and ‘if is_category’ but didn’t work. Maybe it will never work..

Note: the post type and the taxonomy have been created by a plugin. This plugin lets me add ‘posts’ under the new post type and category (taxonomy)

You can see the attached image: https://i.imgur.com/uR2N47d.png

How can I do that?