Extra word appearing at end of related posts excerpt

Hi – I have created a new template as per your instructions. However, the excerpt appears to be including the word “Related” at the end of each related grids item – at the end of each excerpt. I have searched my code but cannot find where this is coming from.
example at: https://bournhall.ooh-websites.co.uk/a-very-special-fathers-day-thanks-to-bourn-hall/ (see related articles at the bottom of the page).

Here’s my functions.php code:

/**Add related posts section**/
add_filter( 'the_content', 'add_related_posts_after_post_content' );
function add_related_posts_after_post_content( $content ) {
 
    //check if it's a single post page.
    if ( is_single() ) {
 
        // check if we're inside the main loop
        if ( in_the_loop() && is_main_query() ) {
 
            // add your own attributes here (between the brackets [ ... ])
            $shortcode = '[related_posts_by_tax posts_per_page="3" title="Related Articles" image_size="large" format="thumbnail_excerpt"]';
 
            // add the shortcode after the content
            $content = $content . $shortcode;
        }
    }
 
    return $content;
}

/*hook in a new related posts grid*/
add_filter( 'related_posts_by_taxonomy_template', 'rpbt_thumbnail_exerpt_format_template', 10, 3 );
 
// Return the right template for the thumbnail_excerpt format
function rpbt_thumbnail_exerpt_format_template( $template, $type, $format ) {
    if ( isset( $format ) && ( 'thumbnail_excerpt' === $format ) ) {
        return 'related-posts-thumbnail-excerpts.php';
    }
    return $template;
}

// Create new format thumbnail_excerpt for use in widget and shortcode
add_action( 'wp_loaded', 'rpbt_thumbnail_excerpt_format', 11 );
 
function rpbt_thumbnail_excerpt_format() {
 
    if ( !class_exists( 'Related_Posts_By_Taxonomy_Defaults' ) ) {
        return;
    }
 
    $defaults = Related_Posts_By_Taxonomy_Defaults::get_instance();
 
    // Add the new format .
    $defaults->formats['thumbnail_excerpt'] = __( 'Thumbnail with excerpt' );
}

// Return posts with post thumbnails for the thumbnail_excerpt format.
add_filter( 'related_posts_by_taxonomy_shortcode_atts', 'rpbt_thumbnail_exerpt_args' ); // shortcode
add_filter( 'related_posts_by_taxonomy_widget_args', 'rpbt_thumbnail_exerpt_args' ); // widget
 
function rpbt_thumbnail_exerpt_args( $args ) {
    if (  'thumbnail_excerpt' === $args['format'] ) {
        $args['post_thumbnail'] = true;
    }
 
    return $args;
}

and here’s the code from my related-posts-thumbnail-excerpts.php file:

<?php if ( $related_posts ) : ?>

 
    <?php foreach ( $related_posts as $post ) :
        setup_postdata( $post );
 
    // Check if size was set in widget or shortcode
    $size = isset( $rpbt_args['size'] ) ? $size : 'large';
?>
 
        <div class="ooh-related-posts-grid">
        <!-- post thumnail -->
        <div class="ooh-related-posts-grid-thumb">
        <?php if ( has_post_thumbnail() ) : ?>
            <a href="<?php the_permalink(); ?>"><?php the_post_thumbnail( $size ); ?></a>
            <div class="ooh-related-posts-grid-date"><?php the_modified_date(); ?></div>
             <!-- title -->
        <div class="ooh-related-posts-grid-title">
        <a href="<?php the_permalink() ?>"><?php the_title(); ?></a>
        </div>
            </div>
        <?php endif; ?>
 
       
 
        <!-- excerpt -->
        <div class="ooh-related-posts-grid-excerpt">
        <?php the_excerpt(); ?></div>
        </div>
    <?php endforeach; ?>
    
 
 
<?php else : ?>
<p><?php _e( 'No related posts found', 'related-posts-by-taxonomy' ); ?></p>

<?php endif ?>

Any help much appreciated!