Drupal 8 - Hook form alter views exposed form

d8-views-exp-form-alter.php

<?php

/**
 * Implements hook_form_alter().
 */
function MYMODULE_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  $view_names = array('my_view_name');
  $view = $form_state->getStorage('view');
  if ($form_id == 'views_exposed_form' && in_array($view['view']->id(), $view_names)) {
    // Do some shilzzle.
  }
}

Hi, this code is working for Drupal 9.5.3 in theme:

function THEMENAME_form_views_exposed_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) { 
    if ($form['#id'] == 'views-exposed-form-all-products-page') {
	 $form['keys']['#attributes']['placeholder'] = 'Product search';
    }
}

My form:

<form data-block="nav_additional" action="/products" method="get" id="views-exposed-form-all-products-page" accept-charset="UTF-8" data-once="form-updated" data-drupal-form-fields="edit-keys">
  <div class="form--inline clearfix">
	<div class="js-form-item form-item js-form-type-textfield form-type-textfield js-form-item-keys form-item-keys">
		<label for="edit-keys">Search</label> 
		<input placeholder="Product search" data-drupal-selector="edit-keys" type="text" id="edit-keys" name="keys" value="" size="30" maxlength="128" class="form-text form-control">
    </div>
	<div data-drupal-selector="edit-actions" class="form-actions js-form-wrapper form-wrapper" id="edit-actions">
		<input data-drupal-selector="edit-submit-all-products" type="submit" id="edit-submit-all-products" value="Search" class="button js-form-submit form-submit btn btn-primary">
	</div>
  </div>
</form>