Seems like a complete database exfiltration. Quora advertisers also had info compromised from a separate email notice:

  - Account information available on the Ads Manager account settings page.
  - The email address provided for notifications about your ad campaigns.
  - Campaign structure and setup, including information like budgets, schedule, bids, targeting, and ad information.
  - Notifications that were in your Ads Manager, such as ad paused, logo approved, and ad ready.
  - Audience setup information available on the Ads Manager audience page such as types and creation date.
  - Partial credit card information, including name, expiration date, and the last four digits of the credit card.