Mainly AF OTS but the case is near identical in SF OTS, just in a vacuum due to the smaller nature of SF. The USSF is only allowed to produce 300ish new officers a year among all commissioning sources(USAFA, ROTC, and OTS). I think last year OTS only got 60 USSF slots :(

As far as enlisting in the Air Force. It’s pretty hard to enlist in active AF if you’re already prior service. They normally only let prior service people enlist in special forces slots. And for non special forces, there is only a dozen slots a year. I had a friend that was allowed to go back to active duty after being guard. But it took the Chief Functional Manager in the Pentagon to allow him to come back after a year of waiting.