Look it depends on the age of the car, but let's take an old manual car for example.

On those cars, there's a fuel map to rpm. There's actually a few maps including throttle and ignition timing. But think of a spreadsheet of rpm and fuel at a certain throttle load.

At 0 throttle: The map says to stop the engine from stealing at under say 800 rpm it needs to have fuel added at rpms lower than that to speed up the engine to avoid stalling. At 800rpm it needs a consistent amount kind of a known amount that keeps it in equilibrium. At over 800rpm it needs less fuel the more rpm it has over the idle 800rpm until it's zero fuel.

And you'll feel that, you'll feel that moment the car starts adding fuel because if you're only engine braking to a stop your car will get near that idle rpm and your engine will start adding power to avoid a stall, and your braking will diminish.