We stop getting paid for days worked after the 30th. The LES that comes out this Thursday (which is the 30th) will be for all of PP20, and we'll get the full PP20 paycheck on Tuesday 10/5.
Then (if the government does shut down) we'll get an LES on Thursday 10/14 that will only cover the the first five days of PP21, and we'll get a partial paycheck for those days on 10/19. After that, no more getting paid.
And that's without getting into the debt ceiling issue, which would be completely unprecedented.
I'm pretty sure free leave isn't a thing any more because they passed a law that made backpay guaranteed (even for people sent home) which is somehow connected.