I managed to fix it but the date displayed over the thumbnail shows the current date instead of the post date.

Changed my content.php inside /template-parts/ to:

<?php
/**
 * Template part for displaying posts.
 *
 * @link https://codex.www.ads-software.com/Template_Hierarchy
 *
 * @package Theme Palace
 * @subpackage Edufication
 * @since Edufication 1.0.0
 */

$options = edufication_get_theme_options();
$readmore = ! empty( $options['read_more_text'] ) ? $options['read_more_text'] : esc_html__( 'Read More', 'edufication' );
$class = has_post_thumbnail() ? '' : 'no-post-thumbnail';
?>

<article id="post-<?php the_ID(); ?>" <?php post_class( $class ); ?>>

    
    <div class="featured-image" <?php if ( has_post_thumbnail() ) : ?> style="background-image: url('<?php the_post_thumbnail_url( 'post-thumbnail' ); ?>');" <?php endif; ?>>
        <a href="<?php the_permalink(); ?>" class="featured-image-link"></a>
        <?php if ( edufication_archive_meta_option( 'hide_date' ) ) : ?>
            <span class="posted-on">
                <time><?php echo get_the_date('d',get_the_id() ); ?> <span class="month"><?php echo  get_the_date('M',get_the_id() ); ?></span></time>
            </span><!-- .posted-on -->
        <?php endif; ?>
    </div>
    

    <div class="entry-container">
        <header class="entry-header">
            <h2 class="entry-title"><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
        </header>

        <div class="entry-meta">
            <?php edufication_article_footer_meta(); ?> 
        </div><!-- .entry-meta -->

        <div class="entry-content">
            <?php the_excerpt(); ?>
        </div><!-- .entry-content -->

        <a href="<?php the_permalink(); ?>" class="view-event"><?php echo esc_html( $readmore ); ?></a>
    </div><!-- .entry-container -->

</article><!-- #post-## -->

There is a background image behind the title of the individual page. How to remove the background image?