diff --git a/lib/Capabilities.php b/lib/Capabilities.php
index c44966a4c..491b5a7fc 100644
--- a/lib/Capabilities.php
+++ b/lib/Capabilities.php
@@ -53,8 +53,7 @@ class Capabilities implements ICapability {
 				'canCreateBoards' => $this->permissionService->canCreate(),
 				'apiVersions' => [
 					'1.0',
-					'1.1',
-					'1.2'
+					'1.1'
 				]
 			]
 		];
diff --git a/lib/Controller/AttachmentApiController.php b/lib/Controller/AttachmentApiController.php
index 244d97abd..debf93f6f 100644
--- a/lib/Controller/AttachmentApiController.php
+++ b/lib/Controller/AttachmentApiController.php
@@ -27,16 +27,13 @@ use OCP\AppFramework\Http;
 use OCP\AppFramework\Http\DataResponse;
 use OCP\IRequest;
 use OCA\Deck\Service\AttachmentService;
-use OCA\Deck\Db\AttachmentMapper;
 
 class AttachmentApiController extends ApiController {
 	private $attachmentService;
-	private $attachmentMapper;
 
-	public function __construct($appName, IRequest $request, AttachmentService $attachmentService, AttachmentMapper $attachmentMapper) {
+	public function __construct($appName, IRequest $request, AttachmentService $attachmentService) {
 		parent::__construct($appName, $request);
 		$this->attachmentService = $attachmentService;
-		$this->attachmentMapper = $attachmentMapper;
 	}
 
 	/**
@@ -52,13 +49,6 @@ class AttachmentApiController extends ApiController {
 				return $attachment->getType() === 'deck_file';
 			});
 		}
-
-		if ($apiVersion === '1.2') {
-			foreach ($attachment as &$attachment) {
-				$this->attachmentMapper->mapOwner($attachment);
-			}
-		}
-
 		return new DataResponse($attachment, HTTP::STATUS_OK);
 	}
 
diff --git a/lib/Controller/AttachmentController.php b/lib/Controller/AttachmentController.php
index 979200271..38334199a 100644
--- a/lib/Controller/AttachmentController.php
+++ b/lib/Controller/AttachmentController.php
@@ -26,31 +26,22 @@ namespace OCA\Deck\Controller;
 use OCA\Deck\Service\AttachmentService;
 use OCP\AppFramework\Controller;
 use OCP\IRequest;
-use OCA\Deck\Db\AttachmentMapper;
 
 class AttachmentController extends Controller {
 
 	/** @var AttachmentService */
 	private $attachmentService;
-	private $attachmentMapper;
 
-	public function __construct($appName, IRequest $request, AttachmentService $attachmentService, AttachmentMapper $attachmentMapper) {
+	public function __construct($appName, IRequest $request, AttachmentService $attachmentService) {
 		parent::__construct($appName, $request);
 		$this->attachmentService = $attachmentService;
-		$this->attachmentMapper = $attachmentMapper;
 	}
 
 	/**
 	 * @NoAdminRequired
 	 */
 	public function getAll($cardId) {
-		$attachments = $this->attachmentService->findAll($cardId, true);
-
-		foreach ($attachments as &$attachment) {
-			$this->attachmentMapper->mapOwner($attachment);
-		}
-
-		return $attachments;
+		return $this->attachmentService->findAll($cardId, true);
 	}
 
 	/**
diff --git a/lib/Db/AttachmentMapper.php b/lib/Db/AttachmentMapper.php
index 07a294a8d..727e3cce1 100644
--- a/lib/Db/AttachmentMapper.php
+++ b/lib/Db/AttachmentMapper.php
@@ -156,14 +156,4 @@ class AttachmentMapper extends DeckMapper implements IPermissionMapper {
 		}
 		return $this->cardMapper->findBoardId($attachment->getCardId());
 	}
-
-	public function mapOwner(Attachment &$attachment) {
-		$attachment->resolveRelation('createdBy', function ($userId) {
-			$user = $this->userManager->get($userId);
-			if ($user !== null) {
-				return new User($user);
-			}
-			return $user;
-		});
-	}
 }
diff --git a/lib/Service/AttachmentService.php b/lib/Service/AttachmentService.php
index b563f0bcf..bf79217cd 100644
--- a/lib/Service/AttachmentService.php
+++ b/lib/Service/AttachmentService.php
@@ -60,6 +60,7 @@ class AttachmentService {
 	private $activityManager;
 	/** @var ChangeHelper */
 	private $changeHelper;
+	/** @var IUserManager */
 	private IUserManager $userManager;
 	/** @var AttachmentServiceValidator */
 	private AttachmentServiceValidator $attachmentServiceValidator;
@@ -71,6 +72,7 @@ class AttachmentService {
 		ChangeHelper $changeHelper,
 		PermissionService $permissionService,
 		Application $application,
+		ICacheFactory $cacheFactory,
 		AttachmentCacheHelper $attachmentCacheHelper,
 		$userId,
 		IL10N $l10n,