Why does the first loop take arguments from the second loop?

Please try below code :

<?php get_header(); ?>
  <main role="main">
    <section class="container">
      <div class="row">
        <div class="col-lg-8">
        <?php if ( have_posts() ) : ?>
          <?php while ( have_posts() ) : the_post(); ?>
          <h1 class="text-center><?php the_title(); ?></h1>
          <?php endwhile; ?>
           <?php wp_reset_postdata(); ?>
        <?php endif; ?>
        
          <div class="row">
          <?php
          $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
          $args = array('post_type'=>'post', 'post_status'=>'publish', 'paged'=>$paged );
          $post_query = new WP_Query($args); ?>
          <?php if ( $post_query->have_posts() ) : ?>
            <?php while ( $post_query->have_posts() ) : $post_query->the_post(); ?>
            <div class="col-lg-4">
              <article class="news-item">
              <?php $image = get_the_post_thumbnail_url(get_the_ID(), 'medium'); ?>
                <a class="news-img" href="<?php echo get_permalink(); ?>" style="background-image: url(<?php echo esc_url($image); ?>);">
                </a>
                <div class="news-copy">
                  <h2 class="news-title"><?php the_title(); ?></h2>
                  <?php the_excerpt(); ?>
                </div>
                <div class="news">
                  <div class="news-date"><?php echo get_the_date( 'd/m/Y' ); ?></div>
                  <a class="btn" href="<?php echo get_permalink(); ?>">
                    <?php if (function_exists('pll_e')) { pll_e('More'); } ?>
                    <i class="ti-angle-right"></i>
                  </a>
                </div>
              </article>
            </div>
            <?php endwhile; ?>
             <?php wp_reset_postdata(); ?>
          <?php else : ?>
            <p><?php if (function_exists('pll_e')) { pll_e('Sorry, xxx...'); } ?></p>
          <?php endif; ?>
          <?php the_posts_pagination(); ?>
          
          </div>
        </div>
      </div>
    </section>
  </main>
<?php get_footer(); ?>