diff --git a/lib/ClustersBackend/FaceRecognitionBackend.php b/lib/ClustersBackend/FaceRecognitionBackend.php
index 92c6c8b4..ef10284c 100644
--- a/lib/ClustersBackend/FaceRecognitionBackend.php
+++ b/lib/ClustersBackend/FaceRecognitionBackend.php
@@ -125,7 +125,7 @@ class FaceRecognitionBackend extends Backend
 
         // Post process
         foreach ($faces as &$row) {
-            $row['id'] = \array_key_exists('name', $row) ? $row['name'] : (int) $row['id'];
+            $row['id'] = $row['name'] ?? (int) $row['id'];
             $row['count'] = (int) $row['count'];
         }
 
diff --git a/lib/ClustersBackend/Manager.php b/lib/ClustersBackend/Manager.php
index aec74324..73463959 100644
--- a/lib/ClustersBackend/Manager.php
+++ b/lib/ClustersBackend/Manager.php
@@ -27,7 +27,11 @@ use OCP\IRequest;
 
 class Manager
 {
-    /** Mapping of backend name to className */
+    /**
+     * Mapping of backend name to className.
+     *
+     * @var array<string, class-string>
+     */
     public static array $backends = [];
 
     /**
@@ -39,20 +43,20 @@ class Manager
      */
     public static function get(string $name): Backend
     {
-        if (!\array_key_exists($name, self::$backends)) {
-            throw new \Exception("Invalid clusters backend '{$name}'");
+        if ($className = self::$backends[$name] ?? null) {
+            /** @var Backend */
+            return \OC::$server->get($className);
         }
 
-        return \OC::$server->get(self::$backends[$name]);
+        throw new \Exception("Invalid clusters backend '{$name}'");
     }
 
     /**
      * Register a new backend.
      *
-     * @param mixed $name
-     * @param mixed $className
+     * @param class-string $className
      */
-    public static function register($name, $className): void
+    public static function register(string $name, string $className): void
     {
         self::$backends[$name] = $className;
     }
diff --git a/lib/ClustersBackend/PlacesBackend.php b/lib/ClustersBackend/PlacesBackend.php
index bdef23dd..499e24ee 100644
--- a/lib/ClustersBackend/PlacesBackend.php
+++ b/lib/ClustersBackend/PlacesBackend.php
@@ -211,8 +211,8 @@ class PlacesBackend extends Backend
             $json = json_decode($otherNames, true);
 
             // Check if the language is available
-            if (\array_key_exists($lang, $json) && \is_string($json[$lang])) {
-                return $json[$lang];
+            if ($translated = ($json[$lang] ?? null)) {
+                return (string) $translated;
             }
         } catch (\Error) {
             // Ignore errors, just use original name
diff --git a/lib/Controller/DaysController.php b/lib/Controller/DaysController.php
index 187c5966..15afe22c 100644
--- a/lib/Controller/DaysController.php
+++ b/lib/Controller/DaysController.php
@@ -187,11 +187,11 @@ class DaysController extends GenericApiController
         // Load details into map byref
         foreach ($details as $photo) {
             $dayId = (int) $photo['dayid'];
-            if (!\array_key_exists($dayId, $drefMap)) {
+            if (!($drefMap[$dayId] ?? null)) {
                 continue;
             }
 
-            if (!\array_key_exists('detail', $drefMap[$dayId])) {
+            if (!($drefMap[$dayId]['detail'] ?? null)) {
                 $drefMap[$dayId]['detail'] = [];
             }
 
diff --git a/lib/Db/LivePhoto.php b/lib/Db/LivePhoto.php
index 175096cc..74c1f93e 100644
--- a/lib/Db/LivePhoto.php
+++ b/lib/Db/LivePhoto.php
@@ -18,21 +18,20 @@ class LivePhoto
      */
     public function isVideoPart(array $exif): bool
     {
-        return \array_key_exists('MIMEType', $exif)
-               && 'video/quicktime' === $exif['MIMEType']
-               && \array_key_exists('ContentIdentifier', $exif);
+        return 'video/quicktime' === ($exif['MIMEType'] ?? null)
+               && !empty($exif['ContentIdentifier'] ?? null);
     }
 
     /** Get liveid from photo part */
     public function getLivePhotoId(File $file, array $exif): string
     {
         // Apple JPEG (MOV has ContentIdentifier)
-        if (\array_key_exists('MediaGroupUUID', $exif)) {
-            return (string) $exif['MediaGroupUUID'];
+        if ($uuid = ($exif['MediaGroupUUID'] ?? null)) {
+            return (string) $uuid;
         }
 
         // Google MVIMG and Samsung JPEG
-        if (\array_key_exists('MicroVideoOffset', $exif) && ($videoLength = $exif['MicroVideoOffset']) > 0) {
+        if (($offset = ($exif['MicroVideoOffset'] ?? null)) && ($offset > 0)) {
             // As explained in the following issue,
             // https://github.com/pulsejet/memories/issues/468
             //
@@ -48,14 +47,14 @@ class LivePhoto
             // and subsequently extract the video file using the
             // EmbeddedVideoFile binary prop, but setting the offset
             // is faster for the same reason mentioned above.
-            $videoOffset = $file->getSize() - $videoLength;
+            $videoOffset = $file->getSize() - $offset;
 
             return "self__traileroffset={$videoOffset}";
         }
 
         // Google JPEG and Samsung HEIC / JPEG (Apple?)
-        if (\array_key_exists('MotionPhoto', $exif)) {
-            if ('image/jpeg' === $exif['MIMEType']) {
+        if ($exif['MotionPhoto'] ?? null) {
+            if ('image/jpeg' === ($exif['MIMEType'] ?? null)) {
                 // Google Motion Photo JPEG
 
                 // We need to read the DirectoryItemLength key to get the length of the video
@@ -90,7 +89,7 @@ class LivePhoto
                 return 'self__trailer';
             }
 
-            if ('image/heic' === $exif['MIMEType']) {
+            if ('image/heic' === ($exif['MIMEType'] ?? null)) {
                 // Samsung HEIC -- no way to get this out yet (DirectoryItemLength is senseless)
                 // The reason this is above the MotionPhotoVideo check is because extracting binary
                 // EXIF fields on the fly is extremely expensive compared to trailer extraction.
@@ -98,7 +97,7 @@ class LivePhoto
         }
 
         // Samsung HEIC (at least S21)
-        if (\array_key_exists('MotionPhotoVideo', $exif) && !empty($exif['MotionPhotoVideo'])) {
+        if (!empty($exif['MotionPhotoVideo'] ?? null)) {
             // It's a binary exif field, decode when the user requests it
             return 'self__exifbin=MotionPhotoVideo';
         }
diff --git a/lib/Db/TimelineQueryDays.php b/lib/Db/TimelineQueryDays.php
index fc20dce7..2e0737df 100644
--- a/lib/Db/TimelineQueryDays.php
+++ b/lib/Db/TimelineQueryDays.php
@@ -276,13 +276,13 @@ trait TimelineQueryDays
         }
 
         // Favorite field, may not be present
-        if (\array_key_exists('categoryid', $row) && $row['categoryid']) {
+        if ($row['categoryid'] ?? null) {
             $row['isfavorite'] = 1;
         }
         unset($row['categoryid']);
 
         // Get hidden field if present
-        if (\array_key_exists('hidden', $row) && $row['hidden']) {
+        if ($row['hidden'] ?? null) {
             $row['ishidden'] = 1;
         }
         unset($row['hidden']);
@@ -294,11 +294,10 @@ trait TimelineQueryDays
         unset($row['datetaken']);
 
         // Calculate the AUID if we can
-        if (\array_key_exists('epoch', $row) && \array_key_exists('size', $row)
-           && ($epoch = (int) $row['epoch']) && ($size = (int) $row['size'])) {
+        if (($epoch = $row['epoch'] ?? null) && ($size = $row['size'] ?? null)) {
             // compute AUID and discard size
             // epoch is used for ordering, so we keep it
-            $row['auid'] = Exif::getAUID($epoch, $size);
+            $row['auid'] = Exif::getAUID((int) $epoch, (int) $size);
             unset($row['size']);
         }
 
@@ -337,8 +336,8 @@ trait TimelineQueryDays
     private function dayIdToMonthId(int $dayId): int
     {
         static $memoize = [];
-        if (\array_key_exists($dayId, $memoize)) {
-            return $memoize[$dayId];
+        if ($cache = $memoize[$dayId] ?? null) {
+            return $cache;
         }
 
         return $memoize[$dayId] = strtotime(date('Ym', $dayId * 86400).'01') / 86400;
diff --git a/lib/Db/TimelineQueryMap.php b/lib/Db/TimelineQueryMap.php
index 190264f5..3b0c3320 100644
--- a/lib/Db/TimelineQueryMap.php
+++ b/lib/Db/TimelineQueryMap.php
@@ -64,22 +64,14 @@ trait TimelineQueryMap
         $res = $this->executeQueryWithCTEs($query)->fetchAll();
 
         // Post-process results
-        $clusters = [];
-        foreach ($res as &$cluster) {
-            $c = [
-                'center' => [
-                    (float) $cluster['lat'],
-                    (float) $cluster['lon'],
-                ],
-                'count' => (float) $cluster['count'],
-            ];
-            if (\array_key_exists('id', $cluster)) {
-                $c['id'] = (int) $cluster['id'];
-            }
-            $clusters[] = $c;
-        }
-
-        return $clusters;
+        return array_map(static fn ($row) => [
+            'id' => (int) $row['id'],
+            'center' => [
+                (float) $row['lat'],
+                (float) $row['lon'],
+            ],
+            'count' => (float) $row['count'],
+        ], $res);
     }
 
     /**
diff --git a/lib/Db/TimelineWrite.php b/lib/Db/TimelineWrite.php
index 5647d0ef..68004b1e 100644
--- a/lib/Db/TimelineWrite.php
+++ b/lib/Db/TimelineWrite.php
@@ -137,8 +137,7 @@ class TimelineWrite
         // Get BUID from ImageUniqueId if not present
         $buid = $prevRow ? $prevRow['buid'] : '';
         if (empty($buid)) {
-            $imageUniqueId = \array_key_exists('ImageUniqueID', $exif) ? $exif['ImageUniqueID'] : null;
-            $buid = Exif::getBUID($file->getName(), $imageUniqueId, (int) $file->getSize());
+            $buid = Exif::getBUID($file->getName(), $exif['ImageUniqueID'] ?? null, (int) $file->getSize());
         }
 
         // Get exif json
diff --git a/lib/Exif.php b/lib/Exif.php
index fa4a5438..1011a061 100644
--- a/lib/Exif.php
+++ b/lib/Exif.php
@@ -161,9 +161,9 @@ class Exif
         // Get timezone from exif
         try {
             $tzStr = $exif['OffsetTimeOriginal']
-                ?: $exif['OffsetTime']
-                ?: $exif['LocationTZID']
-                ?: throw new \Exception();
+                ?? $exif['OffsetTime']
+                ?? $exif['LocationTZID']
+                ?? throw new \Exception();
             $exifTz = new \DateTimeZone((string) $tzStr);
         } catch (\Exception) {
             $exifTz = null;