It is only possible for photos to resurface because they were stored in iCloud for months or maybe years essentially in spite of user intention for those photos to be deleted.
Apple is a heavily lock-in oriented company with ulterior motives and macOS is filled with DRM to boot. That's poorly compatible with the concept or privacy by definition.
It is only possible for photos to resurface because they were stored in iCloud for months or maybe years essentially in spite of user intention for those photos to be deleted.