This makes it harder for russian military to steal one of Mullvad servers to track your porn usage over VPN - once they unplug it, all links to porn will be gone.
That’s not how ram works, at least not generally. Unless frozen to an extremely cold temperature, ram loses its value very quickly and needs constant power to retain data. If a server were to lose power at normal operating temperatures, there would be nothing significant left to recover within a few seconds.
It's nothing that can't be overcome with forensic equipment, though. With the right set of tools you can even take the sticks out of the server while it's still running and retain the data, that's why RAM encryption is a thing. For the really paranoid, homomorphic encryption.
Harder, yes, but still good to note not impossible. There's some cryogenic techniques that allow them to preserve what's on the RAM long enough to read it.
It's a bit of a long shot, and I'm not sure if it's just theory or proven in reality. The idea is that you literally freeze the memory at a cold enough temperature to freeze the state of the memory, and then swap the memory into a machine with power in order to read or dump the data
It's a variation of a cold boot attack. Instead of forcing an OS crash and rebooting into an OS connected to a portable drive, you cool the memory to extend the time you have before the data degrades and can then do whatever you want with it. I believe you can extend it up to a week.
From what I understand it means there’s no persistence on disk of any traffic/data, it’s entirely in memory, so less risk of data being stolen or leaked