Try to use UserNotifications.

src/notifications/managermac.mm

@@ -1,13 +1,12 @@
 #include "manager.h"
 
-#include <Foundation/Foundation.h>
-#include <QtMac>
+#import <UserNotifications/UserNotifications.h>
 
-@interface NSUserNotification (CFIPrivate)
-- (void)set_identityImage:(NSImage*)image;
-@end
+#include <QApplication>
 
-NotificationsManager::NotificationsManager(QObject* parent) : QObject(parent) {}
+NotificationsManager::NotificationsManager(QObject* parent) : QObject(parent) {
+
+}
 
 void NotificationsManager::postNotification(const QString& roomId,
                                             const QString& eventId,
@@ -19,16 +18,37 @@ void NotificationsManager::postNotification(const QString& roomId,
   Q_UNUSED(eventId);
   Q_UNUSED(icon);
 
-  NSUserNotification* notif = [[NSUserNotification alloc] init];
+  UNUserNotificationCenter* center =
+      [UNUserNotificationCenter currentNotificationCenter];
+  UNAuthorizationOptions options = UNAuthorizationOptionAlert + UNAuthorizationOptionSound;
 
-  notif.title = roomName.toNSString();
-  notif.subtitle = QString("%1 sent a message").arg(senderName).toNSString();
-  notif.informativeText = text.toNSString();
-  notif.soundName = NSUserNotificationDefaultSoundName;
+  [center requestAuthorizationWithOptions:options
+   completionHandler:^(BOOL granted, NSError * _Nullable error) {
+    if (!granted) {
+      NSLog(@"Something went wrong");
+    }
+  }];
 
-  [[NSUserNotificationCenter defaultUserNotificationCenter]
-      deliverNotification:notif];
-  [notif autorelease];
+  UNTimeIntervalNotificationTrigger *trigger = [UNTimeIntervalNotificationTrigger triggerWithTimeInterval:300
+                                    repeats:NO];
+
+  UNMutableNotificationContent *content = [UNMutableNotificationContent new];
+
+  content.title = roomName.toNSString();
+  content.subtitle = QString("%1 sent a message").arg(senderName).toNSString();
+  content.body = text.toNSString();
+  content.sound = [UNNotificationSound defaultSound];
+
+  NSString *identifier = QApplication::applicationName().toNSString();
+
+  UNNotificationRequest *request = [UNNotificationRequest requestWithIdentifier:identifier
+                                    content:content trigger:trigger];
+
+  [center addNotificationRequest:request withCompletionHandler:^(NSError * _Nullable error) {
+      if (error != nil) {
+          NSLog(@"Something went wrong: %@",error);
+      }
+  }];
 }
 
 // unused