6 files declare their use of PathValidatorInterface in Zircon Profile 8

LinkFormatter.php in core/modules/link/src/Plugin/Field/FieldFormatter/LinkFormatter.php

Contains \Drupal\link\Plugin\Field\FieldFormatter\LinkFormatter.

MenuLinkContentForm.php in core/modules/menu_link_content/src/Form/MenuLinkContentForm.php

Contains \Drupal\menu_link_content\Form\MenuLinkContentForm.

PathFormBase.php in core/modules/path/src/Form/PathFormBase.php

Contains \Drupal\path\Form\PathFormBase.

Route.php in core/modules/migrate/src/Plugin/migrate/process/Route.php

Contains \Drupal\migrate\Plugin\migrate\process\Route.

ShortcutSetController.php in core/modules/shortcut/src/Controller/ShortcutSetController.php

Contains \Drupal\shortcut\Controller\ShortcutSetController.

SiteInformationForm.php in core/modules/system/src/Form/SiteInformationForm.php

Contains \Drupal\system\Form\SiteInformationForm.