6 files declare their use of EnforcedResponseException in Drupal 9

authorize.php in core/authorize.php

Administrative script for running authorized file operations.

BigPipeResponseAttachmentsProcessor.php in core/modules/big_pipe/src/Render/BigPipeResponseAttachmentsProcessor.php

FieldBlock.php in core/modules/layout_builder/src/Plugin/Block/FieldBlock.php

FieldBlockTest.php in core/modules/layout_builder/tests/src/Kernel/FieldBlockTest.php

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

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

HtmlResponseAttachmentsProcessor.php in core/lib/Drupal/Core/Render/HtmlResponseAttachmentsProcessor.php