Fixed #15777

CHANGELOG.md

@@ -12,6 +12,7 @@
 - Fixed an error that occurred when running the `entrify/global-set` command. ([#15746](https://github.com/craftcms/cms/issues/15746))
 - Fixed a bug where users’ `username` values weren’t getting updated based on email address changes when `useEmailAsUsername` was enabled. ([#15758](https://github.com/craftcms/cms/issues/15758))
 - Fixed a bug where the `hasAlt` asset query param wasn’t working properly. ([#15762](https://github.com/craftcms/cms/issues/15762))
+- Fixed a bug where relational fields could show related elements for other field instances within element indexes. ([#15777](https://github.com/craftcms/cms/issues/15777))
 
 ## 5.4.4 - 2024-09-14
 

src/fields/BaseRelationField.php

@@ -927,6 +927,13 @@ public function getPreviewHtml(mixed $value, ElementInterface $element): string
         /** @var ElementQueryInterface|ElementCollection $value */
         if ($value instanceof ElementQueryInterface) {
             $value = $this->_all($value, $element)->collect();
+        } else {
+            // todo: come up with a way to get the normalized field value ignoring the eager-loaded value
+            $rawValue = $element->getBehavior('customFields')->{$this->handle} ?? null;
+            if (is_array($rawValue)) {
+                $ids = array_flip($rawValue);
+                $value = $value->filter(fn(ElementInterface $element) => isset($ids[$element->id]));
+            }
         }
 
         return $this->previewHtml($value);