There are many VPN services that begin just by reselling white-label VPN solutions, such as provided by NordVPN[1], because it's much cheaper and easier than building your own globally distributed high-capacity and low-latency network. I hope that Mozilla didn't go down this route, as many suspect ProtonVPN did[2], which Mozilla has partnered in the past with[3]. In fact, given that partnership I wouldn't be surprised, if Mozilla VPN was just a rebranded ProtonVPN service underneath. That would bring additional income to Mozilla without taking away any of the development resources from Firefox, and could be seen as a win-win situation by both companies.
[1] https://nordvpn.com/white-label/
[2] https://vpnscam.com/tesonet-data-mining-company-owns-nordvpn...