Conflicting data on the size of one application in the same device

If you're seeing different storage sizes for WhatsApp, it's probably because different sections of your device show different kinds of data. Some might include cache or temporary files, while others don’t. Also, after a big update like iOS 18, it can take a while for the system to fully update the storage information. Restarting your phone might help with that.

For the lost data issue, here’s what you can try: First, check if you have a WhatsApp backup. You can do this by going to WhatsApp > Settings > Chats > Chat Backup. If there's a backup available, you can uninstall and reinstall WhatsApp. During the setup, choose to restore from the backup.

Next, check your iCloud storage to make sure you have enough space. Sometimes, if iCloud is full, it might not have backed up all your data. You can check this under Settings > [Your Name] > iCloud > Manage Storage.

If you don’t have any backups available, then sadly, it might be hard to recover the lost data.

Let me know if this helps!