I don’t know the details of what is being proposed but I think an hybrid PoW/PoS would most likely be a positive. I’m not sure about pure PoS though… Also, I’m not aware of the argument that hybrid PoW/PoS would undermine fungibility.
Some of my thoughts below:
nostr:note1t2jf50ah0fl2gspkas42yjf9fw5kkl24uh2sr9wu3ah78v34q9jsvxu5ez