Multiple hints. Multiple. It doesn’t matter how many, but the simple fact that it’s always more than one is what boggles the damn mind.
I mean, over the years, I’ve come to terms with never really knowing how, but: why? That at least can be delved into, I think. What is it that inspires such courses of action? Is it blithe & blissful ignorance, or actually something more like cogently willful disregard? Is it some collective allure of pushing one’s luck, or some deep-seated need to watch it all burn? 😅
If you want your players to run from a fight, do not make it their choice. You have designed a fight that they can not win and expect them to know they can not win when it is impossible for them to learn that information unless you tell them thus defeating the point of making the fight in the first place. So unless you’re okay with killing members of the party just so they can run away, the only way to ensure they will leave is if you don’t make it their decision.