On something that is inherently non-deterministic? Something which is also to a great extent distilled from other frontier models, meaning it has the possibility to generate similar outputs to those meaning that just pattern detection might also not be as effective? Easier to ban everything that’s open, than try to figure out which one of them is Chinese

Models don't even agree with themselves in terms of returning identical results

Many of these models will report that they are Claude. It’s going to be difficult to overcome reasonable doubt.

Except that even the exact same model won't output the exact same results, that's a fundamental aspect of how LLMs work. They're probabilistic/stochastic, not deterministic.