This is a profound, never-ever-should-happen gap in data security, and it is yet another instance where DigitalOcean comes out looking remarkably amateurish.
Conversationally, I would have expected their hypervisor to have been doing thin provisioning: That until you write data to a block the block is 0s (having no provisioning on actual storage). And if you write 0s, that too isn't actually provisioned on real storage. And when you write actual data, well that is what the block now contains.