Their VPN is a bit pointless at the moment though. They're basically reselling Mullvad. You can get the same servers & more connectivity options (e.g. bypassing their client) for the same price by just going direct.
The point is their client can be agnostic to the backing service. If Mullvad is ever found to have problems (privacy, security, etc), Mozilla can switch to a better service without affecting end users at all.
