It only loads the first 50 MB needed to start the game at first, as you interact/progress it loads more. 50 MB is definitely at the boundary of "how many users appreciate a button vs how many are ignored they have to click it to load the initial page" size.

Having to click a button to see anything itself is even a scammy pattern as it's used by scam sites to get more permissions before the user has a chance to doubt the content at all.

Pretty sure it's just the default Emscripten page. It is bad and most demos don't bother changing it.