6 files declare their use of AccountProxyInterface in Zircon Profile 8

AuthenticationSubscriber.php in core/lib/Drupal/Core/EventSubscriber/AuthenticationSubscriber.php

Contains \Drupal\Core\EventSubscriber\AuthenticationSubscriber.

FormBuilderTest.php in core/tests/Drupal/Tests/Core/Form/FormBuilderTest.php

Contains \Drupal\Tests\Core\Form\FormBuilderTest.

LinkAccessConstraintValidator.php in core/modules/link/src/Plugin/Validation/Constraint/LinkAccessConstraintValidator.php

Contains \Drupal\link\Plugin\Validation\Constraint\LinkAccessConstraintValidator.

PrivateTempStore.php in core/modules/user/src/PrivateTempStore.php

Contains \Drupal\user\PrivateTempStore.

PrivateTempStoreFactory.php in core/modules/user/src/PrivateTempStoreFactory.php

Contains \Drupal\user\PrivateTempStoreFactory.

ProtectedUserFieldConstraintValidator.php in core/modules/user/src/Plugin/Validation/Constraint/ProtectedUserFieldConstraintValidator.php

Contains \Drupal\user\Plugin\Validation\Constraint\ProtectedUserFieldConstraintValidator.