diff --git a/.upgradenotes/MDL-85975-2025092314370040.yml b/.upgradenotes/MDL-85975-2025092314370040.yml
new file mode 100644
index 00000000000..263b753aca2
--- /dev/null
+++ b/.upgradenotes/MDL-85975-2025092314370040.yml
@@ -0,0 +1,17 @@
+issueNumber: MDL-85975
+notes:
+  core:
+    - message: >
+        `restore_qtype_plugin::unset_excluded_fields` now returns the modified
+        questiondata structure,
+
+        in order to support structures that contain arrays.
+
+        If your qtype plugin overrides
+        `restore_qtype_plugin::remove_excluded_question_data` without
+
+        calling the parent method, you may need to modify your overridden method
+        to use the returned
+
+        value.
+      type: fixed
diff --git a/public/backup/moodle2/restore_qtype_plugin.class.php b/public/backup/moodle2/restore_qtype_plugin.class.php
index 52b10c6a548..4b80a13a022 100644
--- a/public/backup/moodle2/restore_qtype_plugin.class.php
+++ b/public/backup/moodle2/restore_qtype_plugin.class.php
@@ -568,8 +568,7 @@ abstract class restore_qtype_plugin extends restore_plugin {
 
         foreach ($excludefields as $excludefield) {
             $pathparts = explode('/', ltrim($excludefield, '/'));
-            $data = $questiondata;
-            self::unset_excluded_fields($data, $pathparts);
+            $questiondata = self::unset_excluded_fields($questiondata, $pathparts);
         }
 
         return $questiondata;
@@ -581,25 +580,60 @@ abstract class restore_qtype_plugin extends restore_plugin {
      * If any of the elements in the path is an array, this is called recursively on each element in the array to unset fields
      * in each child of the array.
      *
-     * @param stdClass|array $data The questiondata object, or a subsection of it.
+     * @param stdClass|array $data The questiondata structure, or a subsection of it.
      * @param array $pathparts The remaining elements in the path to the excluded field.
-     * @return void
+     * @return stdClass|array The $data structure with excluded fields removed.
      */
-    private static function unset_excluded_fields(stdClass|array $data, array $pathparts): void {
+    private static function unset_excluded_fields(stdClass|array $data, array $pathparts): stdClass|array {
         $element = array_shift($pathparts);
-        if (!isset($data->{$element})) {
-            // This element is not present in the data structure, nothing to unset.
-            return;
+        $unset = false;
+        // Get the current element from the data structure.
+        if (is_object($data)) {
+            if (!property_exists($data, $element)) {
+                // This element is not present in the data structure, nothing to unset.
+                return $data;
+            }
+            $dataelement = $data->{$element};
+        } else { // It's an array.
+            if (!array_key_exists($element, $data)) {
+                return $data;
+            }
+            $dataelement = $data[$element];
         }
-        if (is_object($data->{$element})) {
-            self::unset_excluded_fields($data->{$element}, $pathparts);
-        } else if (is_array($data->{$element})) {
-            foreach ($data->{$element} as $item) {
-                self::unset_excluded_fields($item, $pathparts);
+        // Check if we need to recur, or unset this element.
+        if (is_object($dataelement)) {
+            $dataelement = self::unset_excluded_fields($dataelement, $pathparts);
+        } else if (is_array($dataelement)) {
+            foreach ($dataelement as $key => $item) {
+                if (is_object($item) || is_array($item)) {
+                    // This is an array of objects or arrays, recur.
+                    $dataelement[$key] = self::unset_excluded_fields($item, $pathparts);
+                } else {
+                    // This is an associative array of values, check if they should be removed.
+                    $subelement = reset($pathparts);
+                    if ($key == $subelement) {
+                        unset($dataelement[$key]);
+                    }
+                }
             }
         } else if (empty($pathparts)) {
             // This is the last element of the path and it's a scalar value, unset it.
-            unset($data->{$element});
+            $unset = true;
         }
+        // Write the modified element back to the data structure, or unset it.
+        if (is_object($data)) {
+            if ($unset) {
+                unset($data->{$element});
+            } else {
+                $data->{$element} = $dataelement;
+            }
+        } else {
+            if ($unset) {
+                unset($data[$element]);
+            } else {
+                $data[$element] = $dataelement;
+            }
+        }
+        return $data;
     }
 }
diff --git a/public/backup/moodle2/tests/restore_qtype_plugin_test.php b/public/backup/moodle2/tests/restore_qtype_plugin_test.php
new file mode 100644
index 00000000000..527763281fe
--- /dev/null
+++ b/public/backup/moodle2/tests/restore_qtype_plugin_test.php
@@ -0,0 +1,147 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace core;
+
+/**
+ * Tests for question type restore methods
+ *
+ * @package   core
+ * @copyright 2025 onwards Catalyst IT EU {@link https://catalyst-eu.net}
+ * @author    Mark Johnson <mark.johnson@catalyst-eu.net>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @covers    \restore_qtype_plugin
+ */
+final class restore_qtype_plugin_test extends \basic_testcase {
+    /**
+     * All default and specified fields should be removed from the provided data structure.
+     */
+    public function test_remove_excluded_question_data(): void {
+        global $CFG;
+        require_once($CFG->dirroot . '/backup/moodle2/restore_plugin.class.php');
+        require_once($CFG->dirroot . '/backup/moodle2/restore_qtype_plugin.class.php');
+        $data = (object) [
+            // Default excluded fields should be removed.
+            'id' => 1,
+            'createdby' => 2,
+            'modifiedby' => 3,
+            // This field is not specified for removal, it should remain.
+            'questiontext' => 'Some question text',
+            // Excluded paths that address an array should operate on all items in the array.
+            'hints' => [
+                (object) [
+                    'id' => 4,
+                    'questionid' => 1,
+                    // This field is not specified for removal.
+                    'text' => 'Lorem ipsum',
+                ],
+                (object) [
+                    'id' => 5,
+                    'questionid' => 1,
+                    'text' => 'Lorem ipsum',
+                ],
+            ],
+            'options' => [ // This is an array of arrays, rather than an array of objects. It should be handled the same.
+                [
+                    'id' => 6,
+                    'questionid' => 1,
+                    // This field is not specified for removal.
+                    'option' => true,
+                ],
+                [
+                    'id' => 7,
+                    'questionid' => 1,
+                    'option' => false,
+                ],
+                [
+                    'id' => 8,
+                    'questionid' => 1,
+                    'option' => false,
+                ],
+            ],
+            'custom1' => 'Some custom text',
+            // This field is not specified for removal.
+            'custom2' => 'Some custom text2',
+            // Fields specified for removal should be removed even if they contain null values.
+            'custom3' => null,
+            'customarray' => [
+                (object) [
+                    // Null values should also be removed.
+                    'id' => null,
+                    // This field is not specified for removal.
+                    'text' => 'Custom item text',
+                ],
+                (object) [
+                    'id' => null,
+                    'text' => 'Custom item text2',
+                ],
+            ],
+            'customstructure' => [ // This array contains scalar values, not a list of objects/arrays.
+                'id' => null,
+                'text' => 'Custom structure text',
+                'number' => 1,
+                'bool' => true,
+            ],
+        ];
+
+        $expecteddata = (object) [
+            'questiontext' => 'Some question text',
+            'hints' => [
+                (object) [
+                    'text' => 'Lorem ipsum',
+                ],
+                (object) [
+                    'text' => 'Lorem ipsum',
+                ],
+            ],
+            'options' => [
+                [
+                    'option' => true,
+                ],
+                [
+                    'option' => false,
+                ],
+                [
+                    'option' => false,
+                ],
+            ],
+            'custom2' => 'Some custom text2',
+            'customarray' => [
+                (object) [
+                    'text' => 'Custom item text',
+                ],
+                (object) [
+                    'text' => 'Custom item text2',
+                ],
+            ],
+            'customstructure' => [
+                'text' => 'Custom structure text',
+                'number' => 1,
+            ],
+        ];
+
+        $excludedfields = [
+            '/custom1',
+            '/custom3',
+            '/customarray/id',
+            '/customstructure/id',
+            '/customstructure/bool',
+            // A field that is not in the data structure will be ignored.
+            '/custom4',
+        ];
+        $this->assertEquals($expecteddata, \restore_qtype_plugin::remove_excluded_question_data($data, $excludedfields));
+    }
+}