Stopwatch has the following code to detect negative elapsed durations, but this logic only runs during the Stopwatch.Stop call.

If this behavior is worth preserving for stopped Stopwatch instances, I don't see why the responsibility should be shifted to the caller for "active" ones.

I believe this logic should either be removed entirely, or apply to all overloads regardless of IsRunning, possibly including the new GetElapsedTime helpers.

I wouldn't be surprised if some of our own logic is not accounting for the possibility of negative durations.