Probably they bias the RNG for selecting the next token. This can be done practically in a lot of ways, including during training.
I suspect the signal will be significantly under the noise floor, so it's not detectable if you don't know exactly what to look for, but certainly you can submit more information then the textual contents.
I suspect the signal will be significantly under the noise floor, so it's not detectable if you don't know exactly what to look for, but certainly you can submit more information then the textual contents.