After Restore- Same Foto Count - different File size

After transferring from iPhone 12 Pro to 16 Pro, both on iOS 18.0.1 (via iCloud backup restore), I am missing 71GB of photos according to iPhone storage. However, the number of photos in the Photos app remains the same. The “Optimize Photos” option is not activated. Any idea how I can find out where the 71GB went missing?

I have now also activated photo optimization, but even after activation, there is still a difference in storage usage.