Why should I believe them?(OP)
On HN, there is one comment, and it does question if it's true. GOOD!
I am curious if it's real or not. My bet is it's not. It's easy to screw up some downloading logic with overflows, one-off errors etc, but since WA is E2E encrypted, it would need a lot more "accident" in code to make this possible.
> ... With end-to-end encrypted backup, you can also add that same layer of protection to your backup on iCloud or Google Drive.
[1]: https://faq.whatsapp.com/general/chats/about-end-to-end-encr...
My first suspicion would be, "Define new". OP and you could be working on 2 different definitions of that word.
https://old.reddit.com/r/NoStupidQuestions/comments/ry0cnr/d...
https://web.archive.org/web/20220107101132/https://old.reddi...
Edit: The thread has now been deleted, so both reddit threads about this issue are deleted.
TL; DR: photos were from a loaner phone that was never wiped that OP backed up, and then restored onto his new phone.