They run the authoritative nameservers for .dev, so they'll have some information about how much traffic your domain is getting, and from where.
Beyond that (and knowing you own the domain), running the registry doesn't give them any more info than they already get about you & your domain from their other services.
Beyond that (and knowing you own the domain), running the registry doesn't give them any more info than they already get about you & your domain from their other services.