This is what I see instead. I am on Firefox Dev Edition updated to the latest ver. on W11.
Viewing post in Deep in the Spooky, Scary Woods comments
Searching for issues with Twine games in Firefox, I came across this thread: https://intfiction.org/t/twine-games-in-firefox-on-itch-io/62667/3
I hope that helps, and sorry if it doesn't.