It is highly recommended that if you have an iOS 17 backup, that you restore your iPhone using that. To get the old photos app back, you have to completely downgrade iOS, as the app is integrated into the iOS. Apple doesn't provide the IPSW files for iOS 17 anymore, meaning there isn't another safe way of downgrading. A lot of times if you search up how to downgrade iOS, it will ask you to install software that will jailbreak your iPhone. Jailbreaking is an extremely dangerous procedure. If something goes wrong, you could render your phone unusable. And since Apple considers jailbreaking a violation of their terms of service, they can deny you repair service, even if you have a warranty. Even if nothing goes wrong during jailbreaking, you run a greater risk of getting malware. To me, the cons outweigh the pros and I would learn the new interface rather than getting my photos stolen by malware.
Cheers,
Jonasilver137