disable featured image on Image Post Format

add_filter( 'theme_mod_jnews_single_show_featured', 'custom_disable_featured_image' );

/**
 * Disable Featured Image on Image Post Format.
 *
 * @param boolean $flag If featured image showing on single post.
 * @return boolean
 */
function custom_disable_featured_image( $flag ) {
    if ( 'image' === get_post_format() ) {
        return false;
    }
    return $flag;
}