The Belgian news outlet VRT NWS claims to have gained access to audio recordings made as a result of Google Assistant 'listening' to user speech or activity. The recordings were leaked to VRT by a Google subcontractor. This apparent evidence suggests that the search giant allows these workers access to information that would have remained private were it not for the presence of the Assistant.
https://www.notebookcheck.net/Google-Assistant-enabled-devices-allegedly-found-to-listen-in-on-users.427391.0.html