[FabHK]

That’s not what’s commonly understood to be a modern cipher. It would be trivial for a government to make a list of undesired messages/images and find everyone that has forwarded it.

https://en.wikipedia.org/wiki/Chosen-plaintext_attack

[gonehome]

Yeah that’s literally the point in the CSAM case.

For regular people taking photos the government won’t have their plaintext.

For popular media people are uploading the same copy of it saves a lot of bandwidth.