i've recently upgraded my phone and am still waiting for all of my photos in the icloud to appear on my new phone. ive tried airdropping some of them which worked but now my old phone will no longer allow me to do this. my recycle price on the old phone is about to expire but i darent wipe it until i have the photos
Just make sure photo backup is on in iCloud and they will all be saved there for you.
If you have a lot of photos you will have to increase your iCloud storage plan or transfer all your photos to your PC or aptop etc.
They are the thumbnails of your images which may not have fully downloaded yet.
Make sure you have a wifi connection to download them.