Regardless of the marketing material, LLMs are still just using probabilities to guess what the next token is.
you think it should be deterministic?
If LLMs were configured to be deterministic, instead of the current "small amount of randomness to provide the illusion of a thinking machine", they would be much more useful in exchange for being less exciting to laypeople.
In other words, scam.
you know you can set the temperature to zero and get exactly that, right?