It's almost public knowledge as there's an option in the GUI called "scrub data", the absence of a tick there implies that it's not going to be erased before the VMs partition is reassigned. I had a chat to the support months back about "erase data" not being in the API at the time, and the solution I came to was just to ditch their API and go back to scraping their forms for the option.
That said, this would probably go down better for the company and the community if you tried a private disclosure rather than posting about it on Github.