

The hidden prompt is only cheating if the reviewers fail to do their job right and outsource it to a chatbot, it does nothing to a human reviewer actually reading the paper properly. So I won’t say it’s right or ethical, but I’m much more sympathetic to these authors than to reviewers and editors outsourcing their job to an unreliable LLM.
They probably got fed up with a broken system giving up it’s last shreds of legitimacy in favor of LLM garbage and are trying to fight back? Getting through an editor and appeasing reviewers already often requires some compromises in quality and integrity, this probably just seemed like one more.