It seems like you're trying to solve a totally different problem that doesn't exist. If you have a subscription, that means Mullvad must store information that

It seems like you're trying to solve a totally different problem that doesn't exist. If you have a subscription, that means Mullvad must store information that ties your account to the subscription payment processor. That is the information they don't want to store anymore, because they want their users to be anonymous. Their system is already setup so that users can't be correlated with VPN activity.