stealth model
An unreleased model published anonymously, usually on a routing service, so a lab can collect real usage data before putting its name on it.
Every so often a new model appears on a routing service under a placeholder name like a colour, an animal or a Greek letter. Nobody says who made it, it is usually free for a week or two, and it is often surprisingly good. That is a stealth model, and it is a deliberate move rather than a leak.
The lab gets something it cannot buy: thousands of strangers pushing an unannounced model in ways no internal test would, with no press coverage attached and no embarrassment if the results are poor. Users get free access to something capable. The catch is worth remembering before you paste anything sensitive in: you do not know who is running the servers, where they are, or what happens to your inputs.