Standard FLARM is optimized for visual flight, where a warning up to 20 seconds ahead of a conflict is ample. Professional operations are different: crews are often heads-down on the mission, flying instrument procedures or working in dense, mixed traffic.
Extended Alerting lengthens the prediction horizon so warnings arrive earlier — bringing FLARM in line with the timing pilots expect from airliner-style collision-avoidance systems such as TCAS. Alerts flow through to every connected display and instrument exactly as before, just sooner.