This is extremly sad to hear.
I do understand, that for "new features" at some point an upgrade fee would be acceptable, but not providing existing users with some sort of discount is some malpractice and not supporting of longtime users.
I myself bought a lifetime Pro license I think back in 2016 and would willingly upgrade to Premium for a discounted fee, but ~100€ just for the feature to get 2FA and breach notifications? Thank you, but no.