https://wccftech.com/google-maps-for-ios-now-lets-users-report-accidents-and-traffic-slowdowns/

Google Maps will soon bring a new feature to its iOS app which will let users report accidents and traffic slowdowns from their device. This feature was added to the Android Google Maps app last year, and is only now making its way to iPhone and iPad.

To report an incident, tap the new plus button that appears during navigation, to report an incident. The incidents can be reported in any of the following categories for now: