Almost every Pages document has vanished

Why would Apple delete all your documents when they are backed up to iCloud? I don’t understand what the purpose of the back up even is if backing them up also delete them so that you no longer have access to your files. I don’t remember this being a problem and tell the last iPhone update. It seems that updating your iPhone means you get screwed because the iCloud back up really just means your files will be deleted. I don’t understand this. I’m surprised at the app Pages doesn’t work better. That the iCloud backup doesn’t work better. I thought the back up was to help you not hurt you