Your previous 2TB plan was automatically cancelled but you can buy it again. See the following from What happens to your iCloud storage when you sign up for Apple One - Apple Support
If the iCloud storage included in Apple One is equal to your current plan
During the free trial, you keep both your current iCloud+ plan and the iCloud storage in Apple One. Once the trial is finished, your current iCloud+ plan is canceled. Your total iCloud storage will be the amount included in your Apple One subscription.
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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.