After updating the Uber app, we were successfully able to ask Siri to hail us a ride, while tapping on the Ride tab in Apple Maps once again listed Uber as one of the ride-hailing services available alongside Lyft.
While the Siri and Apple Maps integrations are working again in the United States, we encountered errors when trying to hail an Uber with Siri and Apple Maps in Toronto, Canada, where the features were previously supported.
As noted by Christian Zibreg at iDB, some users may need to manually re-enable the Siri and Apple Maps integrations in Settings → Uber → Siri & Search and Settings → Maps under "Ride Booking Extensions."
The ability to hail an Uber ride with Siri or Apple Maps had disappeared in late January following an earlier update to the Uber app. Both features were originally added in iOS 10, and it's unclear what prompted their temporary removal.
Uber's app is available for free on the App Store.