The google-events package structures Firestore types under google.events.cloud.firestore_v1.types, not as a top-level firestore symbol on google.events.cloud. The subpackage name uses an underscore (firestore_v1), not a dot-separated path (firestore.v1).
Use the full path with firestore_v1 (underscore, not dot) and reach into the .types submodule for the DocumentEventData class.
from google.events.cloud.firestore_v1.types import DocumentEventData # parse a CloudEvent payload data = DocumentEventData() data._pb.MergeFromString(event.data)
The types module re-exports DocumentEventData at the firestore_v1 level as well.
from google.events.cloud.firestore_v1 import DocumentEventData