Well, there’s another point of view. Firstly, the data mining claims are just claims and speculations, because they were never proved. Secondly, this whole thing can be seen as an extensive smearing campaign from the competitors, you can read more here for example https://vpnpro.com/blog/confusion-in-the-vpn-industry-is-nor.... So one could argue that it also may apply to ProtonMail since they own ProtonVPN or vice versa. The oldest trick in the book: defame opponents for your own personal gain.
Regarding the Tesonet and its ownership of NordVPN and ProtonVPN, well these are only speculations too.