How to get the View Object from ViewsBlock?
I think there is no way to get the the view Object directly it's protected property and there is no method to get it:
From ViewsBlockBase


  /**
     * The View executable object.
     *
     * @var \Drupal\views\ViewExecutable
     */
    protected $view;


But there is a way first get the view id from the DerivativeId and then load the view here is a code snippet below:

  use Drupal\views\ViewExecutable;

  $blockManager = \Drupal::service('plugin.manager.block');
  $contextRepository = \Drupal::service('context.repository');
  // Get blocks definition.
  $definitions = $blockManager-&gt;getDefinitionsForContexts($contextRepository-&gt;getAvailableContexts());
  $views_blocks = [];
  foreach ($definitions as $id =&gt; $definition) {
    $id_type = explode(':', $id);
    if ($id_type[0] == 'views_block') {
      /** @var \Drupal\views\Plugin\Block\ViewsBlock $viewsBlock */
      $viewsBlock = $blockManager-&gt;createInstance($id);
      $derivativeId = $viewsBlock-&gt;getDerivativeId();
      $derivativeId_exploded = explode('-', $derivativeId);
      $view_id = $derivativeId_exploded[0];
      $view = Views::getView($view_id);
      $views_blocks[] = $view;
    }
  }


I hope that helps.