Also, all of the "situations" where this could be abused are already applicable on all other platforms. There's no reason your Ex couldn't upload CSAM to your Google Photos account, or to your Facebook account. Google Photos and predecessors have scanned since, what, 2013?, and would detect it, and would report it to law enforcement.

Despite this having been a possibility for almost a decade... there's a suspicious lack of headlines of this attack occurring.