That's very odd - no idea why you would be seeing that, as this is the message you get when SharedArrayBuffer is unticked, but I've been sure to tick that for every build I put up (to avoid precisely this issue). Unfortunately, Godot4.x WebGL support isn't completely stable right now.
Have you tried the desktop build?
EDIT: after reading comments elsewhere, it looks like this might come down to the browser you're using. I've never had issues with Firefox, but it also never even occurred to me to test with Edge or Chrome (or anything else for that matter). If I can determine anything further, I'll post some notes on the game page.