BSON objects rendered into the audit log are permitted to exceed the 16MB size threshold. This requirement arises from the need to audit network requests which can exceed the object size. In order to override BSON size limits, template trait overrides can be passed to key serialization methods.

AuditEncryptionCompressionManager::encryptAndEncode invokes BSONObjBuilder::obj without providing a trait. That means, we may attempt to encrypt big inputs, but enforce the 16MB limit on the size of the ciphertext.