How to programmatically load a rendered view exposed filter block
The block content entity is not the block entity that is required there.

The actual block entity is a configuration entity. Use the \Drupal\block\Entity\Block::load method to load it.

Try the following:

$bid = 'exposedformview_nameview_display_name';
$block = \Drupal\block\Entity\Block::load($bid);
$render = \Drupal::entityTypeManager()
        -&gt;getViewBuilder('block')
        -&gt;view($block);
return $render;