WhatsApp is reportedly working on a feature which would allow users to encrypt their Google Drive backups. WhatsApp currently allows Android users to backup their chats to Google Drive, but does not support encryption.
This feature will be available in settings in an upcoming version of WhatsApp. Users will also be able to set a password for their backups, which will be required when restoring the same.
There is no release date for this feature yet, but it is expected to launch soon.