None of those capture the same meaning. Doing something "shitty" has the meaning that it's not just bad or inferior. It's deliberately malicious. and "shit" being the root word in "enshittification" imparts an essence of the same meaning.
Most of these suggestions make it sound like the products/services/apps/whatever in question are kindof inevitably breaking down over time in a way that makes them less useful rather than being leveraged in hostile ways to fuck over their own customers. "Adulteration" at least has a feeling of deliberate sabotage to it, but it still doesn't capture the customer hostility.
Plus, those words aren't unique enough on their own. I'd probably want to prefix them with something else like "platform" or something. "Platform deterioration" for instance.
If I were to come up with an alternative to "enshittification" that captured what I thought was important, maybe something like "creeping capitalistic customer-directed hostile service changes," but that's a mouthful and excludes some things I might consider "enshittification". What about "profit-driven corporate dick moves that make products and services permanently less useful to consumers?"
I dunno. "Enshittification" seems pretty perfect, I think. Everybody knows what it means. Everybody knows it when they see it. Companies do it constantly. And we've needed the term for a long time. It's good that we have it now, I think.