I read in other posts there's some sort of review process and a way to verify if the image is a match or a collision (I don't know much about he details) but I read the latest posts about the attacks that were being worked on.
I mean, with the complexity these attacks have I think it'd be easier for a ransomware gang to just infect you, plant the CSAM, find reliable contact info, verify it, lock your phone and extort your through an untrackable side channel (if this system didn't exist) or something a bit more elaborate / targeted (not even at NSO level).
IDK, I think the phone burns battery for dumber reasons at a higher rate, this should only be activated when there's a new picture written to disk and it's probably less expensive resource wise than whatsapp / telegram / imessage checking for new messages periodically don't you think?
I think if they don't royally fuck the process up or turn it into some idiotic fake way of getting the cops whatever paperwork they need to force you to give them access to your files it's a good thing.