Steps to reproduce (clean Ibexa Experience v3.3.21):

• setup Unsplash (requires valid access keys :
  register at https://unsplash.com/join and setup demo app https://unsplash.com/oauth/applications)

  # config/packages/unsplash.yaml
  
  ezplatform:
      system:
          default:
              content:
                  dam:
                      - unsplash
  dam_unsplash:
      application_id: 'Unsplash : Access Key'
      secret: 'Unsplash : Secret Key'
      utm_source: 'ibexa'
      variations:
          770px:
              fm: jpg
              q: 80
              w: 770
              fit: max

• create a Content Type dam_image for DAM images, which includes the ImageAsset Field
• add & publish Content Object from Content Type dam_image using image from Unsplash
• change & publish the created Content Object
• compare the 2 versions

Result:

TypeError:
Argument 1 passed to eZ\Publish\Core\Repository\SiteAccessAware\ContentService::loadContent() must be of the type int, string given, called in /var/www/html/support/doerken/vendor/ezsystems/ezplatform-kernel/eZ/Publish/Core/MVC/Symfony/View/Builder/ContentViewBuilder.php on line 18 

Expected:
Version Compare should show images side by side