How does engine braking mapping work?

Some recent cars and a lot of bikes can change engine mapping and change engine braking electronically. For instance, my bike is not an automatic bike, so it has mechanical gears and I am able to electronically choose 3 levels of engine braking.

From my understanding, engine mapping consists in changing the proportion of fuel and air depending on a lot of parameter (gas throttle, pressure, temperature, RPM, exhaust data…). During engine break, from what I heard/read, no fuel is injected.

So, how does engine braking mapping work? Does the bike/car inject fuel during engine braking in order to lower it? Or does it change other parameters I’m not aware of?