for the current version of Godot, Web builds will not work without SharedArrayBuffer enabled in the project page settings. although there is a glitch with itch.io. if you are using the Game Jams random submission feature, Godot web games wont work regardless of SharedArrayBuffer, although it can easily be fixed by opening the game page in its own tab. so if you have it enabled and someone still says it doesn't work, its likely they are viewing it through random game jam submissions.