diff --git a/source/client-side-encryption/client-side-encryption.md b/source/client-side-encryption/client-side-encryption.md
index 79005774ef..437c84360b 100644
--- a/source/client-side-encryption/client-side-encryption.md
+++ b/source/client-side-encryption/client-side-encryption.md
@@ -2523,6 +2523,9 @@ explicit session parameter as described in the [Drivers Sessions Specification](
 
 ## Changelog
 
+- 2026-06-16: Update tests in response to server-side validation of payloads
+    ([SERVER-91887](https://jira.mongodb.org/browse/SERVER-91887))
+
 - 2026-05-29: Add stable support for prefix and suffix queries
 
     - Replace `prefixPreview` with `prefix`.
diff --git a/source/client-side-encryption/etc/data/encryptedFields-c10.json b/source/client-side-encryption/etc/data/encryptedFields-c10.json
new file mode 100644
index 0000000000..e9ed08bb39
--- /dev/null
+++ b/source/client-side-encryption/etc/data/encryptedFields-c10.json
@@ -0,0 +1,30 @@
+{
+  "fields": [
+    {
+      "keyId": {
+        "$binary": {
+          "base64": "EjRWeBI0mHYSNBI0VniQEg==",
+          "subType": "04"
+        }
+      },
+      "path": "encryptedIndexed",
+      "bsonType": "string",
+      "queries": {
+        "queryType": "equality",
+        "contention": {
+          "$numberLong": "10"
+        }
+      }
+    },
+    {
+      "keyId": {
+        "$binary": {
+          "base64": "q83vqxI0mHYSNBI0VniQEg==",
+          "subType": "04"
+        }
+      },
+      "path": "encryptedUnindexed",
+      "bsonType": "string"
+    }
+  ]
+}
diff --git a/source/client-side-encryption/etc/data/encryptedFields-prefix-suffix.json b/source/client-side-encryption/etc/data/encryptedFields-prefix-suffix.json
index 141c372dbe..a96e616723 100644
--- a/source/client-side-encryption/etc/data/encryptedFields-prefix-suffix.json
+++ b/source/client-side-encryption/etc/data/encryptedFields-prefix-suffix.json
@@ -18,6 +18,9 @@
                     "strMaxQueryLength": {
                         "$numberInt": "10"
                     },
+                    "contention": {
+                        "$numberLong": "0"
+                    },
                     "caseSensitive": true,
                     "diacriticSensitive": true
                 },
@@ -29,6 +32,9 @@
                     "strMaxQueryLength": {
                         "$numberInt": "10"
                     },
+                    "contention": {
+                        "$numberLong": "0"
+                    },
                     "caseSensitive": true,
                     "diacriticSensitive": true
                 }
diff --git a/source/client-side-encryption/etc/data/encryptedFields-substring.json b/source/client-side-encryption/etc/data/encryptedFields-substring.json
index ee22def77b..d321a32c5c 100644
--- a/source/client-side-encryption/etc/data/encryptedFields-substring.json
+++ b/source/client-side-encryption/etc/data/encryptedFields-substring.json
@@ -21,6 +21,9 @@
                     "strMaxQueryLength": {
                         "$numberInt": "10"
                     },
+                    "contention": {
+                        "$numberLong": "0"
+                    },
                     "caseSensitive": true,
                     "diacriticSensitive": true
                 }
diff --git a/source/client-side-encryption/tests/README.md b/source/client-side-encryption/tests/README.md
index 8598833523..7fcc963b2f 100644
--- a/source/client-side-encryption/tests/README.md
+++ b/source/client-side-encryption/tests/README.md
@@ -1940,6 +1940,13 @@ Read the `"_id"` field of `key1Document` as `key1ID`.
 Drop and create the collection `db.explicit_encryption` using `encryptedFields` as an option. See
 [FLE 2 CreateCollection() and Collection.Drop()](../client-side-encryption.md#create-collection-helper).
 
+Load the file
+[encryptedFields-c10.json](https://github.com/mongodb/specifications/tree/master/source/client-side-encryption/etc/data/encryptedFields-c10.json)
+as `encryptedFields_c10`.
+
+Drop and create the collection `db.explicit_encryption_c10` using `encryptedFields_c10` as an option. See
+[FLE 2 CreateCollection() and Collection.Drop()](../client-side-encryption.md#create-collection-helper).
+
 Drop and create the collection `keyvault.datakeys`.
 
 Insert `key1Document` in `keyvault.datakeys` with majority write concern.
@@ -2014,7 +2021,8 @@ class EncryptOpts {
 
 Store the result in `insertPayload`.
 
-Use `encryptedClient` to insert the document `{ "encryptedIndexed": <insertPayload> }` into `db.explicit_encryption`.
+Use `encryptedClient` to insert the document `{ "encryptedIndexed": <insertPayload> }` into
+`db.explicit_encryption_c10`.
 
 Repeat the above steps 10 times to insert 10 total documents. The `insertPayload` must be regenerated each iteration.
 
@@ -2025,34 +2033,15 @@ class EncryptOpts {
    keyId : <key1ID>,
    algorithm: "Indexed",
    queryType: "equality",
-   contentionFactor: 0,
+   contentionFactor: 10,
 }
 ```
 
 Store the result in `findPayload`.
 
-Use `encryptedClient` to run a "find" operation on the `db.explicit_encryption` collection with the filter
+Use `encryptedClient` to run a "find" operation on the `db.explicit_encryption_c10` collection with the filter
 `{ "encryptedIndexed": <findPayload> }`.
 
-Assert less than 10 documents are returned. 0 documents may be returned. Assert each returned document contains the
-field `{ "encryptedIndexed": "encrypted indexed value" }`.
-
-Use `clientEncryption` to encrypt the value "encrypted indexed value" with these `EncryptOpts`:
-
-```typescript
-class EncryptOpts {
-   keyId : <key1ID>,
-   algorithm: "Indexed",
-   queryType: "equality",
-   contentionFactor: 10,
-}
-```
-
-Store the result in `findPayload2`.
-
-Use `encryptedClient` to run a "find" operation on the `db.explicit_encryption` collection with the filter
-`{ "encryptedIndexed": <findPayload2> }`.
-
 Assert 10 documents are returned. Assert each returned document contains the field
 `{ "encryptedIndexed": "encrypted indexed value" }`.