Data transfer issue

Recently I switched phones from iPhone 7 to iPhone 13, I had over 50 GBs of media on the old phoen so I purchased extra iCloud storage and uploaded it all there. I set up the new phone and everything went fine and I found the photos all appeared in the camera roll when the setup was completed, but what’s strange is that it shows there’s only 4.4 GB of media on the phone??? How?? There’s literally almost 21,000 photos and videos, why is the phone not reading the data correctly? What’s going on?