I'm using "enshittification" as defined here: https://www.merriam-webster.com/slang/enshittification

I believe there's a real chance of it happening here as a result of this transition. I personally experienced results of several of similar transitions over the course of my career. What I haven't experienced are problems with Arxiv that would motivate such a change. There might be actual problems they are trying to solve - but I still believe things will probably get worse as a result.