Oxylabs and Luminati are both residential proxy networks.
Hola is a VPN that sells access to Luminati.
NordVPN is a VPN that does not sell access to anyone. It is not sending anyone else's data through your connection. There's an accusation that it shares ownership with Oxylabs, and that's about it. NordVPN might be buying, not selling, residential proxy access from someone, but it's very unclear if that's true and either way doesn't have a negative impact on their customers.
That is an accusation that Nord or third party partners is turning devices into residential proxies.
It includes a direct quote from Nord on page 5 that says they buy access to IPs, and that the individuals they buy from are "fully aware of the purpose and receive a reward for the traffic sent and received".
Even if you think the "fully aware" part is a lie, I don't think there's any reason to think the part about buying it is a lie.
Even the worst version of a VPN buying IPs from some shady dealer is very different from secretly putting data on their own users' connections. It remains quite misleading to write "oxylabs (NordVPN), luminati (Holla)", implying that Nord is doing the same thing as Hola, of turning their own users into proxies.
A snippet from the article on the residential IP's:
"Furthermore, we conducted realtime device fingerprinting when we captured each IP address. And we have successfully identified the device type and vendor information for 547,497 IP addresses. What surprised us is that 237,029 of them turned out to be IoT systems, such as web camera, DVR, and printer."
Wow that's misleading.
Oxylabs and Luminati are both residential proxy networks.
Hola is a VPN that sells access to Luminati.
NordVPN is a VPN that does not sell access to anyone. It is not sending anyone else's data through your connection. There's an accusation that it shares ownership with Oxylabs, and that's about it. NordVPN might be buying, not selling, residential proxy access from someone, but it's very unclear if that's true and either way doesn't have a negative impact on their customers.