adding icloud storage to apple one

See the following from What happens to your iCloud storage when you sign up for Apple One - Apple Support

If you need more iCloud storage

After you subscribe to Apple One, you can buy more iCloud storage if you need more. With both Apple One and an iCloud+ plan, you can have up to 4TB of total iCloud storage.

Not that I've heard of. Also they usually immediately update their support pages when they make a change like that. You may want to use the Get Support link at the top right of this page to contact support.