Federal workers have always gotten paid when the government shuts down. Some lawyer sees this as a get rich opportunity. The ones that come up short are the essential workers that have to work while the non essentials get free vacation time.
Not 100% true. It takes an act of Congress, after the shutdown is over, to retroactively give them back pay. Which then the President has to sign.
Up to now, that has been the case. But it's not a guarantee.