When you are using a Custom Post Type with its Custom Post Taxonomies, you could need to detect if a particular category is displayed in a post. So, I write a simple WordPress shortocode you can use to detect a particular category and then display the content of the post.

To achieve that, you can add the following code in your functions.php file:

<?php

add_shortcode( 'wp_is_category_cpt', 'wp_is_category_cpt' );

if ( ! function_exists( 'wp_is_category_cpt' ) ) {

  function wp_is_category_cpt( $atts = [], $content = null )
  {
    global $post;

    $defaults = [
      'post_type' => false,
      'taxonomy'  => false,
      'category'  => false,
    ];

    $atts = shortcode_atts( $defaults, $atts, 'wp_is_category_cpt' );

    if ( empty( $atts[ 'post_type' ] ) || empty( $atts[ 'taxonomy' ] ) || empty( $atts[ 'category' ] ) ) {
      return $content;
    }

    if ( $post->post_type === $atts[ 'post_type' ] && has_term( $atts[ 'category' ], $atts[ 'taxonomy' ] ) ) {
      return $content;
    }

    return "";
  }
}

Next, in your post content you can use:

[wp_is_category_cpt post_type="wp_cpt" taxonomy="wp_tax" category="cars"]
  This content will be visible when this post is displayed
  by "wp_cpt" custom post type, in the category "cars" for taxonomy "wp_tax"
[/wp_is_category_cpt]

The wp_cpt and wp_tax are the Custom Post Type slug id and Custom Post Taxonomy slug id. The category argument is the category slug.