[reaperducer]

If it’s at rest encrypted you generally do not manage to get 4TB of data before anyone notices.

If you're talking about your own personal hard drive in your home, yes.

But in this case, we're talking about a huge company conducting literally billions of database queries for tens of thousands of clients an hour.

You only have to have a listening post in one small part of the system that can see things in plaintext for a short time in order to accumulate 4TB in a matter of days.