It's been some time since I played Hopworld. Your recent post reminded me about it, so I tried it to check the new world generation. Right away I noticed there was no music. The different music for each room is one of the things I remembered most about my previous playthrough, but now I don't hear that. Sound still works, so it's not just an audio issue. To make sure, I tried with multiple different browsers (Firefox, Chromium, Safari), but none played music. Did you remove that?
Is it possible to play older versions of the game? Quite a while ago I made an effort to map the entire world of seed 0. I still have that map, but after the world generation was overhauled (probably the changes you described in the January 2023 blog post), I can no longer play that world.