Photos from the old device not loading

I’ve recently changed to a new iPhone and the transferred photos from my previous one are just black screens. It says that there isn’t enough iCloud storage but there was plenty of space when I checked in the settings. When I click on a photo there’s a message that a higher quality version of it cannot be load. I tried restarting my phone, nothing changed. I really don’t want to lose the photos, what should I do?