Block Editor - Block Template

blocks-testimonial.php

<?php
$testimonial = get_field('testimonial');
$author = get_field('author');
$avatar = get_field('avatar');

$id = 'testimonial-' . $block['id'];
?>
<blockquote class="testimonial" id="<?php echo $id; ?>">
  <p><?php echo $testimonial; ?></p>
  <cite>
    <img src="<?php echo $avatar['url']; ?>" alt="<?php echo $avatar['alt']; ?>">
    <span><?php echo $author; ?></span>
  </cite>
</blockquote>