Not quite; Chat Control hearkens back to Apple’s doomed attempt at on-device CSAM filtering - the idea is that on-device images and message contents would be scanned for known hashes. This means a nation state could go fishing on devices for known content, but it wouldn’t allow them to indiscriminately sift through all the content at rest — they’d have to know what they were looking for.

That’s where the steganography comes in, because the hash based approach will fail if the content they’re looking for is obscured in some manner.