diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2645001740b..897cd6b291e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 - Fixed a bug where admin table header cells weren’t indicating when they were sorted. ([#15897](https://github.com/craftcms/cms/issues/15897))
 - Fixed an error that occurred when creating a database backup, if the System Name contained any quote-like characters. ([#15933](https://github.com/craftcms/cms/issues/15933))
 - Fixed a bug where buttons could bleed out of their containers. ([#15931](https://github.com/craftcms/cms/issues/15931), [#15946](https://github.com/craftcms/cms/pull/15946))
+- Fixed a PHP error. ([#15915](https://github.com/craftcms/cms/issues/15915))
 - Fixed an information disclosure vulnerability.
 
 ## 4.12.7 - 2024-10-15
diff --git a/src/services/Elements.php b/src/services/Elements.php
index 71179d82539..736b9a94e23 100644
--- a/src/services/Elements.php
+++ b/src/services/Elements.php
@@ -64,6 +64,7 @@
 use craft\validators\HandleValidator;
 use craft\validators\SlugValidator;
 use DateTime;
+use Illuminate\Support\Collection;
 use Throwable;
 use UnitEnum;
 use yii\base\Behavior;
@@ -2452,7 +2453,7 @@ public function getRecentActivity(ElementInterface $element, ?int $excludeUserId
             ->indexBy('id')
             ->all();
 
-        $activity = [];
+        $activity = Collection::make();
         /** @var ElementActivity[] $activityByUserId */
         $activityByUserId = [];
         $elements = [];
@@ -2468,7 +2469,7 @@ public function getRecentActivity(ElementInterface $element, ?int $excludeUserId
                     $newerRecord->type === ElementActivity::TYPE_VIEW &&
                     $result['type'] !== ElementActivity::TYPE_VIEW
                 ) {
-                    array_splice($activity, array_search($newerRecord, $activity), 1);
+                    $activity = $activity->filter(fn(ElementActivity $record) => $record !== $newerRecord);
                     unset($activityByUserId[$result['userId']]);
                 } else {
                     continue;
@@ -2501,15 +2502,16 @@ public function getRecentActivity(ElementInterface $element, ?int $excludeUserId
                 $elements[$elementKey][$result['siteId']] = $resultElement;
             }
 
-            $activity[] = $activityByUserId[$result['userId']] = new ElementActivity(
+            $record = $activityByUserId[$result['userId']] = new ElementActivity(
                 $users[$result['userId']],
                 $elements[$elementKey][$result['siteId']],
                 $result['type'],
                 DateTimeHelper::toDateTime($result['timestamp']),
             );
+            $activity->push($record);
         }
 
-        return $activity;
+        return $activity->values()->all();
     }
 
     /**