There are many reasons why an app would want to be notified of a call taking place - e.g., a music app could use this event to auto-pause playback, Teams might set the availability status to "busy", etc.
The question is what should happen if such an app takes an excessively long time handling the event. In this case, the OS should not wait for the app and should directly go on making the call. The bug seems to be that the OS did wait, so a misbehaving app can effectively block phone calls by e.g. going into an infinite loop.
The question is what should happen if such an app takes an excessively long time handling the event. In this case, the OS should not wait for the app and should directly go on making the call. The bug seems to be that the OS did wait, so a misbehaving app can effectively block phone calls by e.g. going into an infinite loop.