Date field doesn't allow attributes

My custom form date field is set up as follows:

$form['right']['validfrom'] = array(
      '#type' => 'date',
      '#title' => $this->t('Start date'),
      '#description' => $this->t('The beginning date.'),
      '#attributes' => array('class' => array('lala')),
    );

And the error thrown is the following:

Notice: Undefined index: type in Drupal\Core\Render\Element\Date::processDate() (line 63 of /var/www/website/public_html/core/lib/Drupal/Core/Render/Element/Date.php)
#0 /var/www/website/public_html/core/includes/bootstrap.inc(548): _drupal_error_handler_real(8, 'Undefined index...', '/var/www/website...', 63, Array)
#1 /var/www/website/public_html/core/lib/Drupal/Core/Render/Element/Date.php(63): _drupal_error_handler(8, 'Undefined index...', '/var/www/website...', 63, Array)
#2 [internal function]: Drupal\Core\Render\Element\Date::processDate(Array, Object(Drupal\Core\Form\FormState), Array)
#3 /var/www/website/public_html/core/lib/Drupal/Core/Form/FormBuilder.php(981): call_user_func_array(Array, Array)
#4 /var/www/website/public_html/core/lib/Drupal/Core/Form/FormBuilder.php(1044): Drupal\Core\Form\FormBuilder->doBuildForm('vehicle_main_fo...', Array, Object(Drupal\Core\Form\FormState))
#5 /var/www/website/public_html/core/lib/Drupal/Core/Form/FormBuilder.php(1044): Drupal\Core\Form\FormBuilder->doBuildForm('vehicle_main_fo...', Array, Object(Drupal\Core\Form\FormState))
#6 /var/www/website/public_html/core/lib/Drupal/Core/Form/FormBuilder.php(557): Drupal\Core\Form\FormBuilder->doBuildForm('vehicle_main_fo...', Array, Object(Drupal\Core\Form\FormState))
#7 /var/www/website/public_html/core/lib/Drupal/Core/Form/FormBuilder.php(314): Drupal\Core\Form\FormBuilder->processForm('vehicle_main_fo...', Array, Object(Drupal\Core\Form\FormState))
#8 /var/www/website/public_html/core/lib/Drupal/Core/Controller/FormController.php(74): Drupal\Core\Form\FormBuilder->buildForm('vehicle_main_fo...', Object(Drupal\Core\Form\FormState))
#9 [internal function]: Drupal\Core\Controller\FormController->getContentResult(Object(Symfony\Component\HttpFoundation\Request), Object(Drupal\Core\Routing\RouteMatch))
#10 /var/www/website/public_html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array)
#11 /var/www/website/public_html/core/lib/Drupal/Core/Render/Renderer.php(574): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#12 /var/www/website/public_html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(124): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure))
#13 /var/www/website/public_html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array)
#14 [internal function]: Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}()
#15 /var/www/website/public_html/vendor/symfony/http-kernel/HttpKernel.php(144): call_user_func_array(Object(Closure), Array)
#16 /var/www/website/public_html/vendor/symfony/http-kernel/HttpKernel.php(64): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
#17 /var/www/website/public_html/core/lib/Drupal/Core/StackMiddleware/Session.php(57): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#18 /var/www/website/public_html/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(47): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#19 /var/www/website/public_html/core/modules/page_cache/src/StackMiddleware/PageCache.php(99): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#20 /var/www/website/public_html/core/modules/page_cache/src/StackMiddleware/PageCache.php(78): Drupal\page_cache\StackMiddleware\PageCache->pass(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#21 /var/www/website/public_html/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(47): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#22 /var/www/website/public_html/modules/devel/webprofiler/src/StackMiddleware/WebprofilerMiddleware.php(38): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#23 /var/www/website/public_html/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(50): Drupal\webprofiler\StackMiddleware\WebprofilerMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#24 /var/www/website/public_html/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#25 /var/www/website/public_html/core/lib/Drupal/Core/DrupalKernel.php(652): Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#26 /var/www/website/public_html/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#27 {main}.

I've tested that this happens with whatever attribute you try to set and works perfectly when no attribute set.

EDIT adding more debugging info:

The code in /core/lib/Drupal/Core/Render/Element/Date for the relevant parts is:

class Date extends FormElement {

  /**
   * {@inheritdoc}
   */
  public function getInfo() {
    $class = get_class($this);
    return [
      '#input' => TRUE,
      '#theme' => 'input__date',
      '#process' => [[$class, 'processDate']],
      '#pre_render' => [[$class, 'preRenderDate']],
      '#theme_wrappers' => ['form_element'],
      '#attributes' => ['type' => 'date'],
      '#date_date_format' => 'Y-m-d',
    ];
  }

  /**
   * Processes a date form element.
   *
   * @param array $element
   *   The form element to process. Properties used:
   *   - #attributes: An associative array containing:
   *     - type: The type of date field rendered.
   *   - #date_date_format: The date format used in PHP formats.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   * @param array $complete_form
   *   The complete form structure.
   *
   * @return array
   *   The processed element.
   */
  public static function processDate(&$element, FormStateInterface $form_state, &$complete_form) {
    // Attach JS support for the date field, if we can determine which date
    // format should be used.
    if ($element['#attributes']['type'] == 'date'&& !empty($element['#date_date_format'])) {
      $element['#attached']['library'][] = 'core/drupal.date';
      $element['#attributes']['data-drupal-date-format'] = [$element['#date_date_format']];
    }
    return $element;
  }

The sequence the code is processed is:

1. Creation of field in custom form code
2. Date::getInfo()
3. Date::processDate()
4. Date::preRenderDate - not relevant here

So now if I dpm($element) in Date::processDate()

when there's no attributes set in my field the element seems to have the attributes returned from Date::getInfo() :

But when I set attributes from my own field declaration they seem to override the attributes all together:

All my other fields work fine with attributes just the date seems to be going crazy.