Missing photos and videos after iCloud backup on iPhone

I had no idea bt after some automatic backup and update a lot of photos and videos of mine are missing. They are not even in the recently deleted. I tried everything like syncing and relogging . I had bought a new iphone first half of my picture were missing there . I sold that phone now my this old phone had all pictures bt those first half pictures are missing from here. Even my recent notes updates are updated to my old ones. Help me as i need those pictures. I have storage too . What is this apple???

[Re-Titled by Moderator]

Original Title: Icloud backup photos lost