iphone 12 pro transfer lost hundreds of photos

I recently got an iPhone 12 Pro to replace my iPhone 8 Plus and when the transfer took place I apparently lost hundreds of photos. The only way it appears to remedy this is to factory reset the phone and go to an older iCloud backup to restore. This is problematic since I spent hours after the transfer dealing with about 20 apps that wouldn't download after 24 hours of waiting. In fact, Pages, Numbers and the Apple Store apps were grayed out, but wouldn't let me delete them and re-download. I had to sign out of iCloud, then sign back in and restart my iPhone in order to finish correcting the apps issue. What's the point of having iCloud if it doesn't restore your data properly? I don't have time to set everything back up. I just sold my iPhone 8 Plus, which had been wiped. I'm so angry and frustrated with Apple right now! Who knows how many grand-baby photos or other cherished photos I've lost in this transfer, likely never to be recovered.