diff --git a/core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php b/core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php
index fb1f3c18bf6110373d565da057ac940172b01ec7..7f159bba81e76cbdc4725d335228d8a1f6c9ebfd 100644
--- a/core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php
+++ b/core/modules/content_translation/tests/src/Functional/ContentTranslationSyncImageTest.php
@@ -138,7 +138,7 @@ public function testImageFieldSync() {
     // Populate the test entity with some random initial values.
     $values = [
       'name' => $this->randomMachineName(),
-      'user_id' => mt_rand(1, 128),
+      'user_id' => 2,
       'langcode' => $default_langcode,
     ];
     $entity = \Drupal::entityTypeManager()
diff --git a/core/modules/field/tests/src/Kernel/Entity/Update/SqlContentEntityStorageSchemaColumnTest.php b/core/modules/field/tests/src/Kernel/Entity/Update/SqlContentEntityStorageSchemaColumnTest.php
index 1f3233f28de57d51bab94c9a854ac4471a1d9bb1..b466017a1862d416de1b246cf7a288b7660a5727 100644
--- a/core/modules/field/tests/src/Kernel/Entity/Update/SqlContentEntityStorageSchemaColumnTest.php
+++ b/core/modules/field/tests/src/Kernel/Entity/Update/SqlContentEntityStorageSchemaColumnTest.php
@@ -88,7 +88,7 @@ protected function setUp(): void {
 
     // Create an entity with field data.
     $this->entity = EntityTestRev::create([
-      'user_id' => mt_rand(1, 10),
+      'user_id' => 2,
       'name' => $this->randomMachineName(),
       $field_name => $this->randomString(),
     ]);
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
index fe4e5e95eed020f308eec5b3d7099e5aa4aa6762..c31a29fd5180ec70a29edd612e37553a470a7902 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
@@ -158,7 +158,7 @@ protected function doTestMultilingualProperties($entity_type) {
     $langcode_key = $this->entityTypeManager->getDefinition($entity_type)->getKey('langcode');
     $default_langcode_key = $this->entityTypeManager->getDefinition($entity_type)->getKey('default_langcode');
     $name = $this->randomMachineName();
-    $uid = mt_rand(0, 127);
+    $uid = 2;
     $langcode = $this->langcodes[0];
 
     // Create a language neutral entity and check that properties are stored
@@ -206,6 +206,8 @@ protected function doTestMultilingualProperties($entity_type) {
       if ($langcode != $default_langcode) {
         $properties[$langcode] = [
           'name' => [0 => $this->randomMachineName()],
+          // Note that the user ID here is intentionally random, which is not
+          // what we normally do in tests.
           'user_id' => [0 => mt_rand(128, 256)],
         ];
       }
@@ -593,7 +595,7 @@ protected function doTestLanguageFallback($entity_type) {
     $values = [];
     foreach ($this->langcodes as $langcode) {
       $values[$langcode]['name'] = $this->randomMachineName();
-      $values[$langcode]['user_id'] = mt_rand(0, 127);
+      $values[$langcode]['user_id'] = 2;
     }
 
     $default_langcode = $this->langcodes[0];
diff --git a/core/tests/Drupal/KernelTests/Core/TempStore/TempStoreDatabaseTest.php b/core/tests/Drupal/KernelTests/Core/TempStore/TempStoreDatabaseTest.php
index d1b16c59deec4f45c62f571ae602a031260f7a53..20acd1083b6c90250ce7ff6996f090f9d8c88f04 100644
--- a/core/tests/Drupal/KernelTests/Core/TempStore/TempStoreDatabaseTest.php
+++ b/core/tests/Drupal/KernelTests/Core/TempStore/TempStoreDatabaseTest.php
@@ -39,7 +39,8 @@ public function testSharedTempStore() {
     );
     $collection = $this->randomMachineName();
 
-    // Create two mock users.
+    // Create two mock user IDs. Note that the user IDs are intentionally
+    // random, which is not what we normally do in tests.
     for ($i = 0; $i <= 1; $i++) {
       $users[$i] = mt_rand(500, 5000000);