I've been thinking about this for about a year. In my head I've called it "context bombs", though that may not be super accurate.

Think back to the movie The Manchurian Candidate. Produce highly capable LLM models then give them away for free. Train them with key phrases/codes etc to perform nefarious actions later when those codes are present in some piece of ingested context.

There were a couple of papers written on the topic in 2018 (I think, I'll need to find them again) and there's been surprisingly little more work done on the topic since. At least from what I've seen.

I really love the use of local models over subscription services but personally I would never recommend using open weights models from certain sources in a commercial environment.