Our process is designed to prevent that from happening. The set of image hashes used for matching are from known, existing images of CSAM that have been acquired and validated by child safety organizations. Apple does not add to the set of known CSAM image hashes.
The problem is not that Apple can't add images to the database but that organizations from the outside can inject any hashes to the new, constantly sniffing system at the heart of iOS, padOS and macOS. Apple has no way to verify those or any hashes before they get injected into the database.
If the system detects any matches only some overworked and underpaid content checker from Bangladesh is there to stop your life from being destroyed by some SWAT team crashing through your front door at 3am, killing your barking dog. And who knows if those foreign sweatshops are even trustable.