Nit: they have a partnership with Tailscale to offer the VPN as a part of a tailnet that subscribes to the service.

But, it's not white label. White label implies it would be Tailscale VPN (or similar) with no reference to Mullvalad in their docs or marketing. But that's not what is happening with their offering.

and they've been accepting bitcoin since 2010. I assume they've done very well from that (I'm afraid to calculate what the present value of my mullvad subscription would be)