The reviewer may not be looking at the original image. But rather the visual derivative created during the hashing process and sent as part of the safety vouche

The reviewer may not be looking at the original image. But rather the visual derivative created during the hashing process and sent as part of the safety voucher. In this scenario you could create an image that looks like anything, but where it’s visual derivative is CSAM material. Currently iCloud isn’t encrypted, so Apple could just look at the original image. But in future is iCloud becomes encrypted, then the reporting will be don’t entirely based on the visual derivative. Although Apple could change this by include a unique crypto key for each uploaded images within their inner safety voucher, allowing them to decrypt images that match for the review process.