ICloud photos disappear after updating to iOS 14

Hello,

I am using an iphone 11 pro max with 256 GB storage and I have 50 GB of storage on iCloud. When I updated to iOS 14, all the photos retrieved from iCloud have disappeared and the only photos remained are the ones locally on the phone ( not the ones I restored from an iCloud backup). I tried to restore an old back up again to get the lost photos, but I could not find these photos anywhere and I did not find any old backups.