Yeah, just read a bit more, where it’s implied that Vivaldi recommend you share your Vivaldi account recovery with Proton, which was the problem recently:

https://help.vivaldi.com/desktop/privacy/proton-vpn-for-vivaldi/

Allow Vivaldi to share your account’s recovery email address with Proton (only shown during first use).

https://www.theregister.com/2025/03/27/vivaldi_proton_vpn/

Proton VPN is operated by the same company behind the encrypted email service, Proton Mail. The business found itself in hot water in 2024 after complying with a legal request to hand over the recovery email address for a Proton Mail account.

Hmm… this doesn’t sound good to me.