In good faith, (as someone who's never made it into a FAANG, but who's severely burnt out before) I would speculate that one of the few ways an org could metaphorically do this, would be to threaten your ability to work for anyone else or in the country, which could take a variety of forms including holding your visa hostage or colluding with other companies to ensure you're unemployable.

Either way, being in this position would have massive hypothetical implications, especially if you have any dependents or real reason to fear for your life/future/health back in your home country.

In my past situations, I've used the comparison to being waterboarded—which would seem hyperbolic to anyone reading who's never experienced it, but feels pretty appropriate to me—since it wasn't quite as severe of an existential threat as having to leave the country, but it felt like I was metaphorically blindfolded and having buckets of water thrown in my face while I gasped for air, and the consequence of not just trying to keep breathing meant I'd likely spend the next year without an income and not be able to pay off long-standing debts that are ever-increasing with interest.

Just people who are polyglots.