Unable to restore backup from iCloud in iPhone 12 pro max

I have a big-time issue in restoring data from cloud. Here is the situation

  1. I traded the iPhone 6s and bought iPhone 12 Pro Max

  2. before trading I took backup of all my data on iCloud , then reset it and traded.

  3. Now when I started the new iPhone 12 Pro Max, I got an option under App & Data to restore data from iCloud

  4. I successfully signed in but later it is showing No Backups Available however, I could see the data on iCloud too by log in into browser.

  5. I did not take backup using iTune hence could not restore it from my PC.

Here is the status of my cloud backup, it says incomplete too. But not sure if this is the case than will I able to take the backup again that exists on iCloud ?

enter image description here