I also created a Google Workspace support ticket (#57441148) and confirm that the reply I received back was:
Google Workspace
Hello Dave,
Thank you for contacting Google Workspace Support. My name is Sudheer. I will be taking ownership of this case and will be working with you.
I understand that the guardians are receiving the blank email summaries. We’ve confirmed this is an ongoing issue on our end.This issue has been filed as a bug and our internal product team is working on it and hope it will get fixed soon. I will be updating you with a response once I get an update from the internal product team.
We appreciate your collaboration,patience and understanding through this matter and we will be in touch with you shortly. This case will remain open in the meantime.
Have a great day!
Sincerely,
Sudheer |22:00 - 07:00 IST (UTC+5.5)
Google Workspace Support