Yeah there's definitely some overlap. Lots of dark UX is used for enshittification but sometimes enshittification is just plainly bold bad UX for the sake of making money with a hint of "Yeah it's bad. What are you going to do about it?"

On the other hand, enshittification is part of a cycle that starts with a service that grows dominant at least in part by providing a great experience, only to tear that experience down when it gets in the way of making money. Dark UX isn't always part of that cycle. Plenty of services of all sizes use these patterns right from the start. Not really accurate to call it "enshittification" when it was always just shit.