6 files declare their use of CacheableNormalization in Drupal 10

FieldItemNormalizerTest.php in core/modules/jsonapi/tests/src/Kernel/Normalizer/FieldItemNormalizerTest.php

LinkCollectionNormalizerTest.php in core/modules/jsonapi/tests/src/Kernel/Normalizer/LinkCollectionNormalizerTest.php

NodeTest.php in core/modules/jsonapi/tests/src/Functional/NodeTest.php

NormalizerBase.php in core/modules/jsonapi/src/Normalizer/NormalizerBase.php

ResourceObjectNormalizerCacherTest.php in core/modules/jsonapi/tests/src/Kernel/EventSubscriber/ResourceObjectNormalizerCacherTest.php

ResourceResponseSubscriber.php in core/modules/jsonapi/src/EventSubscriber/ResourceResponseSubscriber.php