In my experience, this is what actually happens. A developer makes a low-quality, low-effort prototype under the assumption it won’t ship. Someone sees it. It gets shipped. Everyone loses.

Sabotage your prototypes then. Have it reset its state every 5 minutes or deliberately leak memory.

Sneaky move.... but then, in the eyes of some people, you might well appear not competent to put together a working system, so make sure you know your audience.

Ya, this basically.

It helps if you have tests because when prototyping, you can write things in a way which break tests and ideally break other features. It works enough that you can validate the one idea. That way it will never pass CI.

They are cunning. You cannot sabotage it enough to fool them.