When building this project for UWP, you will see that the build gets stuck for ~30 seconds on "Cleaning up old IL2CPP generated file" step. However, if you look at the profiler, you'll see that it was in fact the next step (RunIL2CPP) that is taking those 30 seconds.
Reproducible in: 2020.3.23f1
Not reproducible in: 2022.1.0a15