The only thing we can do, is ask where they were going.
Or estimate, based on the provided route (purple, only displayed when a route was set) and driven route (green, only displayed until xxx meter from your start or end point, due to privacy rules).
And analyse the nearest intersection for false turn restrictions, wrong angles on turn-segments, etc.

The more you check, the more experience you gain, the easier it gets to find an error. But still, a lot of them, can't be solved, if we don't get extra info