That's interesting. How does the website possibly detect that I'm on a cellular network when I'm a) use Firefox (which doesn't implement the NetworkInformation API) and b) use a VPN to either a data center or my home server? What about iOS devices using Apple's pseudo-Tor (because Safari doesn't expose NetworkInformation either), or devices using tethered WiFi?
I don't believe this claim at all. This makes me take all their other claims they make with a massive grain of salt as well.
There's also the massive privacy issue: other people will know what websites you visit by simply using the P2P system, and the entire thing seems to be opt-in unless you use an adblocker. That last part shows that the devs know of the privacy issue but have decided to take the practical approach of not fixing the issue and only doing the bare minimum to remove their website from blocklists.
It's only a matter of time before someone will make a tool that enumerates all IPs in the Arc network together with the content they've been served. This one is going onto my Pihole's blocklist...